EA011827B1 - Process for producing high-purity dyalkyl carbonate on commercial scale - Google Patents

Abstract

This invention provides a specific production process in which a high-purity diaryl carbonate usable as a starting material for a high-quality and high-performance polycarbonate using, as a starting material, a reaction mixture containing an alkyl aryl carbonate produced by transesterification of a dialkyl carbonate with an aromatic monohydroxy compound can be produced on a commercial scale of not less than one ton per hr stably over a long period of time. The above starting material is subjected to transesterification using a reaction distillation column. The high-boiling reaction mixture obtained from a bottom of the reaction distillation column is supplied to three specific continuous multistage distillation columns in the following order: a high-boiling substance separation column A, a diaryl carbonate purification column B, and a medium-boiling substance separation column C, whereby a high-purity diaryl carbonate substantially free from medium-boiling by-products, high-boiling by-products and the like can be obtained as a side-cut component in the purification column B on a commercial scale of not less than one ton/hr stably over a long period of time.

Description

The present invention relates to an industrial process for the production of high purity diaryl carbonate. More specifically, the present invention relates to an industrial method for the production of high purity diaryl carbonate, which is used as a raw material in a method for producing polycarbonate by transesterification, by using as a starting material a reaction mixture containing an alkyl aryl carbonate obtained by transesterification between a dialkyl carbonate and an aromatic monohydroxy compound and carrying out the reaction transesterification using a reaction distillation column and then subjecting it to high ipyaschuyu reaction mixture containing a diaryl carbonate thus obtained, the separation and purification using three continuous multi-stage distillation columns, each of which has a specific structure.

State of the art

High purity diphenyl carbonate is an important raw material for the production of aromatic polycarbonate, which is most widely used in structural plastics, without the use of toxic phosgene. As a method for the production of aromatic carbonate, a method of reacting an aromatic monohydroxy compound with phosgene has long been known, and in recent years this method has also been the subject of a number of studies. However, the problem of this method is the use of phosgene and, in addition, in the aromatic carbonate obtained using this method, there are chlorinated impurities that are difficult to separate, and therefore, such aromatic carbonate cannot be used as a raw material for the production of aromatic polycarbonate. Since these chlorinated impurities significantly inhibit the polymerization reaction in the transesterification method, which is carried out in the presence of an extremely small amount of a basic catalyst, for example, even if such chlorinated impurities are present in an amount of only 100 ppm, the polymerization practically does not proceed. To make it possible to use aromatic carbonate as a raw material for the polycarbonate transesterification process, complex multi-stage separation / purification processes are required, such as efficient washing with dilute aqueous alkaline solution and hot water, oil / water separation, distillation, etc. In addition, the yield of aromatic carbonate decreases due to losses due to hydrolysis and losses during distillation during such separation / purification processes. Thus, there are many problems of an economic nature in carrying out this method on an industrial scale.

On the other hand, a method for producing aromatic carbonates by a transesterification reaction between a dialkyl carbonate and an aromatic monohydroxy compound is also known. However, all such transesterification reactions are equilibrium reactions. The equilibrium is strongly biased towards the original system, and the reaction rate is low, therefore, there are many problems in the industrial production of aromatic carbonates using this method. Two types of proposals can be made to solve the difficulties described above.

There are developments of catalysts for increasing the reaction rate, and there are attempts to design the reaction system in such a way as to balance as much as possible in the direction of the reaction product system and thereby improve the yield of aromatic carbonate. For example, for the reaction between dimethyl carbonate and phenol, a method is proposed in which methanol formed as a by-product is azeotroped with an azeotrope forming agent; a method in which methanol formed as a by-product is removed by adsorption on molecular sieves; and a method in which, using a plant in which a distillation column is equipped at the top of the reactor, the alcohol formed in the reaction as a by-product is distilled off from the reaction mixture and, at the same time, unreacted starting material that evaporates is separated by distillation (see Patent Document 1: examples Japanese Patent Application Laid-Open No. 56-123948; Corresponds to US Patent No. 4,182,726).

However, such reaction systems are generally batch systems or batch systems. Since there are limitations on the reaction rate due to the development of a catalyst for such transesterification reactions, and the reaction rates are still low, it is accordingly believed that a periodic system is preferable to a continuous system. However, a continuous reactor mixing system in which a distillation column is provided at the top of the reactor is proposed as a continuous system; but there are problems, such as the remaining low reaction rate and the remaining small gas / liquid interface based on the volume of the liquid. Therefore, it is impossible to obtain a high conversion.

Accordingly, it is difficult to achieve the goal of producing aromatic carbonate continuously in large quantities over an extended period of time using the methods described above, and many problems need to be solved before an economical industrial implementation is possible.

The authors of the present invention have developed methods of reactive distillation, in which such a transesterification reaction is carried out in a continuously operating multi-stage distillation

- 1 011827 column simultaneously with separation by distillation, and the first to establish that the reaction distillation system is beneficial in the case of the transesterification reaction under consideration. For example, a reactive distillation process is proposed in which the dialkyl carbonate and aromatic hydroxy compound are continuously fed into a multi-stage distillation column and the reaction is carried out continuously inside the column in which the catalyst is present, while the low boiling point components containing alcohol formed as a by-product are continuously removed by distillation, and continuously withdrawing the component containing the formed alkylaryl carbonate from the bottom of the column (see Patent Document 2: Japanese Patent Laid-Open application No. 3-291257); a reaction distillation method in which an alkyl aryl carbonate is continuously fed into a multi-stage distillation column, and the reaction is carried out continuously inside a column in which a catalyst is present, while a low boiling point component containing a dialkyl carbonate formed as a by-product from distillation is continuously withdrawn and a component containing the resulting diaryl carbonate from the bottom of the column (see Patent Document 3: Japanese Patent Application Laid-open No. 4-9358); a reaction distillation method in which said reactions are carried out using two continuous multi-stage distillation columns, and therefore the diaryl carbonate is produced continuously, thereby dialkyl carbonate produced as a by-product is efficiently recycled (see Patent Document 4: Japanese Patent Application Laid-Open No. 4- 211038); and a reaction distillation method in which a dialkyl carbonate and an aromatic hydroxy compound or similar compounds are continuously fed into a multi-stage distillation column, and the liquid that flows through the column is withdrawn from the side outlet at an intermediate stage and / or at the lowest stage of the distillation column and introduced into the reactor, placed outside the distillation column so as to induce a reaction, and then introduced back through the circulation inlet equipped at the stage above the stage where the outlet is equipped, resulting in a reaction flows in both the reactor and the distillation column (see Patent Document 5: Japanese Laid-Open Patent Application No. 4-224547; Patent Document 6: Japanese Laid-Open Patent Application No. 4-230242; Patent Document 7: Japanese Laid-open Patent Application No. 4- 235951).

The contemplated reaction distillation methods proposed by the applicants first made it possible to produce aromatic carbonates continuously and efficiently, and a large number of such reaction distillation systems based on the above observations were proposed later (see patent document 8: international publication No. 00/18720 (corresponding to US patent No. 5362901); Patent Document 9: Italian Patent No. 01255746; Patent Document 10: Japanese Laid-Open Patent Application No. 6-9506 (Corresponds to European Patent No. 0560159 and US Patent No. 52829 26); Patent Document 11: Japanese Laid-Open Patent Application No. 6-41022 (Corresponds to European Patent No. 0572870 and US Patent No. 5362901); Patent Document 12: Japanese Laid-open Patent Application No. 6-157424 (Corresponds to European Patent No. 0582931 and US Patent No. 5334742); Patent Document 13: Japanese Laid-Open Patent Application No. 6-184058 (corresponding to European Patent No. 0582930 and US Patent No. 5344954); Patent Document 14: Japanese Laid-open Patent Application No. 7-304713; Patent Document 15: Japanese Patent Application Laid-Open No. 9-40616; Patent Document 16: Japanese Laid-Open Patent Application No. 9-59225; Patent Document 17: Japanese Patent Application Laid-open No. 9-110805; Patent Document 18: Japanese Patent Application Laid-open No. 9-165357; Patent Document 19: Japanese Patent Application Laid-open No. 9-173819; Patent Document 20: Japanese Patent Application Laid-Open No. 9-176094; Patent Document 21: Japanese Patent Application Laid-Open No. 2000-191596; Patent Document 22: Japanese Patent Application Laid-Open No. 2000-191597; Patent Document 23: Japanese Patent Application Laid-open No. 9-194436 (corresponding to European Patent No. 0785184 and US Patent No. 5705673); Patent Document 24: International Publication No. 00/18720 (Corresponds to US Patent No. 6093842); Patent Document 25: International Publication No. 01/042187 (corresponds to published Japanese translation of PCT Application No. 2003-516376); Patent Document 26: Japanese Laid-Open Patent Application No. 2001-64234; Patent Document 27: Japanese Laid-Open Patent Application No. 2001-64235; Patent Document 28: International Publication No. 02/40439 (Corresponds to US Patent No. 6596894, US Patent No. 6596895 and US Patent No. 6600061)).

Among the reaction distillation systems, the applicants of the present invention have also proposed, as a method, which makes it possible to obtain aromatic carbonates of high purity stably over a long period of time without the need for a large amount of catalyst, a method in which a high boiling material containing a catalytic component is reacted with an active substance and then separated, and the catalytic component is recycled (see patent document 29: international publication No. 97/11049 (respectively European Patent No. 0855384 and US Patent No. 5872275)), and a process carried out while maintaining the weight ratio of the polyhydric aromatic hydroxy compound in the reaction system to the catalytic metal of not more than 2.0 (see Patent Document 30: Japanese Patent Application Laid-open No. 11- 92429 (corresponding to European patent No. 1016648 and US patent No. 6262210)). In addition, the applicants of the present invention also proposed a method in which from 70 to 99 wt.% Phenol produced

- 2 011827 as a by-product in the polymerization process, used as a starting material, and diphenyl carbonate can be produced using a reaction distillation method. Such diphenyl carbonate can be used as a starting material for polymerization to produce aromatic polycarbonates (see patent document 31: Japanese Patent Application Laid-open No. 9-255772 (corresponding to European Patent No. 0892001 and US Patent No. 5747609)).

However, in all the documents of the prior art, which proposed the production of aromatic carbonates using the reaction distillation method, there is no report of any process or device that provides the possibility of mass production on an industrial scale (for example, not less than 1 t / h), nor any description suggesting such a process or device. For example, data related to heights (H | and H ₂ ), diameters (E | and E ₂ ), number of stages (N1 and Ν ₂ ) and feed rates of the starting material (C ₁ and C ₂ : kg / h) for two reaction distillation columns, described mainly for the production of diphenyl carbonate (DFK, EDS) from dimethyl carbonate and phenol, are summarized in the table below. one.

Table 1

Ηι ϋι Νι Ωι n ₂ ϋ ₂ Ν ₂ β ₂ Patent document 600 25 twenty 66 600 25 twenty 23 4 350 2,8 - 0.2 305 5-10 15 + nozzle 0.6 12 500 5 fifty 0, 6 400 8 fifty 0.6 fifteen one hundred 4 - 1.4 200 4 - 0.8 sixteen 300 5 40 1,5 - 5 25 0.7 twenty 1200 twenty 40 86 600 25 twenty 31 29th thirty 600 - twenty 66 600 - twenty 22 31

In other words, the largest pairs of continuous multi-stage distillation columns used in the reaction using the reaction distillation system are the columns disclosed by the applicants of the present invention in patent documents 30 and 31. As shown in table. 1, the maximum values for various parameters in the case of continuous multi-stage distillation columns described for the above reaction are H ₁ = 1200 cm, H ₂ = 600 cm, E ₁ = 20 cm; B ₂ = 25 cm; Νχ = Ν ₂ = 50 cm (patent document 15), Ρχ = 86 kg / h and (^ ₂ = 31 kg / h, and the amount of diphenyl carbonate produced did not exceed about 6.7 kg / h, which is not an industrially produced amount.

As methods for separating a diaryl carbonate from a reaction mixture containing a diaryl carbonate, which is obtained by a transesterification reaction and a similar reaction between a dialkyl carbonate and an aromatic monohydroxy compound, as starting material, as described above, and then purifying the diaryl carbonate, crystallization methods, distillation methods, etc. are proposed. As for distillation methods, three methods are proposed. One of them is a method in which diaryl carbonate is obtained as a top product from a column from a distillation column; For example, there are:

I) a method in which a reaction mixture containing a catalyst is distilled as it is in a batch distillation column and diphenyl carbonate is obtained as a top product from the column (see Example 2 of Patent Document 10);

II) a method in which a reaction mixture containing a catalyst is subjected to flash evaporation, and thus a high boiling material containing a large part of the catalyst is separated and a low boiling material, and then the low boiling material is distilled in a distillation column to recover the starting material, and diphenyl carbonate containing the catalyst is obtained as a bottom product from a column, and then said lower product from a column is distilled in a purification column, whereby diphenyl carbonate is obtained as a top product from a column us (see Patent Document 33: Example 1 in Japanese Laid-Open Patent Application No. 4-100824; Patent Document 34: Japanese Laid-open Patent Application No. 9-169704); and

III) a method in which a reaction mixture containing a catalyst is distilled in a distillation column (or evaporation column), and thus separated into a high boiling material containing most of the catalyst and a low boiling material, then the low boiling material is subjected to subsequent continuous distillation using a distillation unit comprising three columns, i.e. a light fraction separation column, a methyl phenyl carbonate separation column and a diphenyl carbonate separation column, as a result, diphenyl carbonate is obtained in ide top product from column (See. Patent Document 17).

Another method is a method in which diaryl carbonate is obtained from a distillation column as a bottom product from a column; for example, there is:

Iv) a method in which a reaction mixture containing a catalyst is distilled in a distillation column, and thus separated into a high boiling material containing most of the catalyst

- 3 011827 RA, and a low boiling material and then a low boiling material are distilled in a distillation column, and diphenyl carbonate is obtained as a bottom product from the column (see Patent Document 26).

Another is a method in which diaryl carbonate is obtained from a distillation column as a product discharged to the side of the column; For example, there are:

V) a method in which a reaction mixture containing a catalyst is introduced into a third reaction distillation column and an additional reaction and distillation are carried out, whereby diphenyl carbomate is obtained as a product withdrawn from the side of the reaction distillation column (see patent documents 12 and 13);

(VI) a method in which a reaction mixture containing a catalyst is subjected to flash evaporation and, as a result, is separated into a high boiling material containing most of the catalyst and a low boiling material, and then the low boiling material is introduced into the distillation column and distillation is carried out, as a result get diphenyl carbonate in the form of a product taken sideways from the reaction distillation column (see Patent Documents 30 and 31; Patent Document 35: International Publication No. 92/18458 (corresponding to US Patent No. 546207);

Vii) a method in which a reaction mixture containing a catalyst is distilled in a first purification column, and as a result, it is separated into a high boiling material containing most of the catalyst and a low boiling material, and then a low boiling material is introduced into the second distillation column and distillation is carried out, as a result, diphenyl carbonate is obtained in the form of a product laterally from the second purification column (see Patent Document 36; Japanese Patent Application Laid-open No. 1149727); and

VIII) a method in which diphenyl carbonate containing phenyl salicylate is introduced into a distillation column having a number of theoretical stages from 5 to 15, and distillation is carried out at a temperature of the lower part of the column of at least 150 ° C., as a result, diphenyl carbonate is obtained as a side-discharge product from a distillation column (see patent document 32: Japanese Patent Application Laid-open No. 9-194437 (corresponding to European Patent No. 0784048)).

However, it has been shown that with such separation / purification methods of diaryl carbonate using the distillation methods discussed, various problems remain. More specifically, the purity of diphenyl carbonate obtained by the method described above (I) is low, and, moreover, this method is a batch process and, therefore, is not suitable for mass industrial production. Regarding method II), the method of patent document 33 is a batch method, and the diphenyl carbonate obtained by the method described in patent document 34 contains a titanium catalyst, although in an amount of not more than 1 ppm, and therefore is not acceptable as a raw material for the production of colorless polycarbonate of high purity. Regarding the method described above III), since diphenyl carbonate is heated to a high temperature in the lower part of each of the two distillation columns, i.e. in the light separation column and in the methyl phenyl carbonate separation column, and then subjected to high temperature in the diphenyl carbonate separation column, diphenyl carbonate is subject to change, which leads to a decrease in purity and lower yield, and this is undesirable. Indeed, the diphenyl carbonate obtained in Example 1 of Patent Document 17 contains approximately 300 ppm of high boiling point by-products. The process of method IV) described above, in which diphenyl carbonate is obtained from the bottom of the column, is not acceptable since the purity is low and therefore the desired polycarbonate cannot be produced.

Since in the process of method V described above) a reaction mixture containing all of the catalyst, unreacted starting material and impurities is introduced from the bottom of the second reaction distillation column to the third reaction distillation column through its upper part, and diphenyl carbonate is removed from the side outlet of the third reaction distillation column , fumes or fog of the starting material, impurities, catalyst, etc .; therefore, the purity of the diphenyl carbonate obtained is low. The processes of the above methods VI and VII are preferred, but in this case there is no mention of the presence of impurities with intermediate boiling points having a boiling point between the alkyl aryl carbonate and diaryl carbonate. Moreover, with regard to the method described above VIII), although it is claimed that the content of phenyl salicylate is reduced from 3000 to 50 ppm (example 2 of patent document 32), nothing is mentioned about any other impurities. For example, although in this example diphenyl carbonate is produced using the phosgene method, and therefore there is a clear process for purifying phenyl carbonate containing chlorinated impurities, nothing is mentioned about chlorinated impurities (which have a negative effect on polymerization to produce polycarbonate and the properties of polycarbonate are even extremely low amount of only a few tens of hours / billion). Using this process, these chlorinated impurities are not separated sufficiently and, therefore, the use of diphenyl carbonate as a raw material for polycarbonate is impossible. From the above data, it is obvious that the chlorine content is 30 ppm in diphenyl carbonate (in which, after washing with alkaline hot water and hot water, and then water, the low-boiling material is removed by distillation, and the resulting diphenyl carbonate, which does not contain water, is purified by distillation) obtained in comparative example 1 of patent document 37 (Japanese Patent Application Laid-open No. 11-12230;

- 4 011827 this application is sent for consideration more than one year after patent document 32), which discloses a similar cleaning method as the method described above.

In addition, in patent document 32, as a method for assessing the purity of diphenyl carbonate obtained by distillation, the temperature and time at which phenol begins to be distilled off when this reaction is carried out with bisphenol A are indicated, but this test method does not evaluate whether diphenyl carbonate is suitable for polymerization. This is explained by the fact that even in the case of diphenyl carbonate of such low purity that the polycarbonate of the required degree of polymerization cannot be obtained, the initial reaction, in which phenol is eliminated, proceeds sufficiently. Moreover, since in this estimation method a large amount of ΝαΟΗ (2.3 ppm) based on bisphenol A is used as a catalyst, even in the case of diphenyl carbonate containing, for example, 1 ppm chlorinated impurities, there could be incorrect assessment was given that diphenyl carbonate has high purity and is acceptable as a raw material for polycarbonate. As previously stated, diphenyl carbonate containing 1 ppm of chlorinated impurities cannot be used as a raw material for polycarbonate. In conventional polymerization, since such a large amount of alkaline catalyst is not used, this evaluation method is not acceptable for determining the purity of diphenyl carbonate, which should be used to produce polycarbonate. In addition, in patent document 32 there is no specific description of any method for purification of diphenyl carbonate obtained by transesterification. Since the types and contents of impurities differ in the case of diphenyl carbonate obtained using the phosgenic method, and in the case of diphenyl carbonate obtained using the transesterification method, it cannot be said that diphenyl carbonate of the same purity will be obtained using the same purification method. Therefore, it cannot be said at all that diphenyl carbonate having the necessary purity as a raw material for polycarbonate will be obtained using the purification method of patent document 32. Moreover, the purified amount of diphenyl carbonate disclosed in patent document 32 is 0.57 kg / h, which not an industrial quantity.

The reaction mixture obtained as the bottom product from the column when using a reaction mixture containing an alkyl aryl carbonate as the starting material, obtained by transesterification between a dialkyl carbonate and an aromatic monohydroxy compound, continuously feeding this starting material to the reaction distillation column, which is a continuously operating multi-stage distillation column, into which contains a homogeneous catalyst, and during the transesterification and distillation reactions in the column ki simultaneously generally contains small amounts of various reaction by-products in addition to the diaryl carbonate, the starting material and catalyst. Such by-products are known to include by-products having a lower boiling point than the boiling point of the aromatic monohydroxy compound used as starting material, such as alkylaryl ether (e.g., anisole), and by-products having a higher boiling point than the boiling point of diaryl carbonate, such as aryloxycarbonyl (hydroxy) arenes (e.g. phenyl salicylate) and aryloxycarbonyl (aryloxycarboxyl) arenes, and methods for separating them are provided. For example, methods for separating anisole (see patent documents 16, 17 and 20) and methods for separating phenyl salicylate (see patent documents 32 and 36) are provided.

When conducting a more detailed study of the processes for the continuous production of diaryl carbonate, the applicants of the present invention found that in addition to these well-known impurities, by-products with intermediate boiling points that have a boiling point between the boiling points of alkylaryl carbonate and diaryl carbonate are also present. To date, there have been no documents that at least somehow revealed the presence of such by-products with intermediate boiling points or methods for their removal.

It has been found that if diaryl carbonate, in which the amounts of such by-products with intermediate boiling points and high-boiling by-products have not been reduced to a sufficient level, is used as a raw material for the production of polycarbonate by transesterification, these by-products with intermediate boiling points and high-boiling by-products cause discoloration and deterioration of the properties of the produced polycarbonate. Thus, it is necessary, as far as possible, to reduce the quantities of both by-products with intermediate boiling points and high-boiling by-products. Therefore, there is a need for a method that makes it possible to obtain high purity diaryl carbonate having a low content of both by-products with intermediate boiling points and high-boiling by-products, and necessary for the production of high-quality and high-performance aromatic polycarbonate, stable for a long period time in an industrial amount of not less than 1 t / h

Description of the invention

The purpose of the present invention is to develop a special process that makes it possible to produce diaryl carbonate of high purity, which can be used as raw material for high-quality and high-performance polycarbonate, one hundred

- 5 011827 batch for a long period of time on an industrial scale of not less than 1 t / h, when using as starting material a reaction mixture containing alkylaryl carbonate obtained by transesterification between dialkyl carbonate and aromatic monohydroxy compound.

Since the applicants of the present invention have disclosed a process for the production of aromatic carbonates using a continuously operating multi-stage distillation column, various proposals have been made regarding the processes for producing reaction mixtures containing aromatic carbonates using a reaction distillation method. However, all these proposals were carried out on a small scale and with a short time of work in the laboratory; and a description of a specific method or installation that makes it possible to realize mass production on an industrial scale from such a reaction mixture of high purity diaryl carbonate, which can be used as raw material for high-quality and having good performance polycarbonate. Therefore, the applicants of the present invention conducted research aimed at developing a specific method that provides the possibility of obtaining high-purity diaryl carbonate, which is of importance as a raw material for high-quality and having good performance polycarbonate, is stable for a long time on an industrial scale in an amount of not less than 1 t / hours As a result, applicants have achieved the objective of the present invention.

Advantages of the Present Invention

It has been found that due to the implementation of the present invention, high-purity diaryl carbonate, which can be used as a raw material for high-quality and having good technical characteristics polycarbonate, can be produced on an industrial scale in an amount of not less than 1 t / h, preferably not less than 2 t / h, more preferably not less than 3 t / h, stably for a long period of time, not less than 2000 h, preferably not less than 3000 h, more preferably not less than 5000 h, from the reaction mixture containing alkylaryl carbonate obtained by transesterification between a dialkyl carbonate and an aromatic monohydroxy compound.

Brief Description of the Drawings

FIG. 1 is a schematic representation of a reaction distillation column for implementing the present invention; and

FIG. 2 is a schematic representation of a high purity diaryl carbonate production plant for carrying out the present invention, wherein a reaction distillation column, a high boiling material separation column A, a diaryl carbonate purification column B and an intermediate boiling material separation column C are connected together; each of these continuous multistage distillation columns includes installed in them internal elements having a predetermined number of stages.

1: gas outlet; 2: fluid outlet; 3 and 4: input; 5: last plate; B: main (main) part (cm); Ό: inner diameter of the main part (cm); ά ₁ : internal diameter of the gas inlet (cm); ά ₂ : inner diameter of fluid outlet (cm); 101, A1, B1, C1: input; B2 and C2: lateral overhead output; 106: withdrawing the top product from the column (low boiling point reaction mixture) of the reaction distillation column; 111: withdrawing the bottom product from the column (high boiling point mixture) of the reaction distillation column; 103, 13, 23, 43: withdrawal of the top gas of the column; 104, 14, 24, 44, 108, 18, 28, 38, 48: heat exchanger; 105, 15, 25, 45: injection of liquid reflux; 16: withdrawal of the top product from the column (A _T ) of the high-boiling material separation column A; 11: withdrawal of the lower product from the column (AB) of the high-boiling material separation column A; 107, 17, 27, 47: withdrawal of the bottom liquid of the column; 26: withdrawal of the top product from the column (B _T ) of the diaryl carbonate B purification column 31: withdrawal of the lower product from the column ( _B ) of the diaryl carbonate B purification column; 33: withdrawal of the product from the side of the column (B ₈ ) of the diaryl carbonate B purification column; 46: withdrawal of the top product from the column (C _t ) of the material separation column with an intermediate boiling point C; 51: withdrawal of the lower product from the column (C _B ) of the material separation column with an intermediate boiling point C; 53: withdrawal of the product from the side of the column (C _d ) of the material separation column with an intermediate boiling point C.

BEST MODE FOR CARRYING OUT THE INVENTION

Further, the present invention is described in more detail.

The dialkyl carbonate used in the present invention is a compound represented by the general formula (22):

K / OSOOK. ¹ (22), where K ¹ represents an alkyl group containing from 1 to 10 carbon atoms, an alicyclic group containing from 3 to 10 carbon atoms or an aralkyl group containing from 6 to 10 carbon atoms. Examples of K ¹ are alkyl groups such as methyl, ethyl, propyl (isomers), allyl, butyl (isomers), butenyl (isomers), pentyl (isomers), hexyl (isomers), heptyl (isomers), octyl (isomers), nonyl (isomers), decyl (isomers) and cyclohexylmethyl; alicyclic groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and cycloheptyl; and aralkyl groups such

- 6 011827 as benzyl, phenethyl (isomers), phenylpropyl (isomers), phenylbutyl (isomers) and methylbenzyl (isomers). The above alkyl groups, the alicyclic group and the aralkyl group may be substituted with other substituents, such as a lower alkyl group, a lower alkoxy group, a cyano group or a halogen atom, and may also contain an unsaturated bond.

Examples of dialkyl carbonates having the aforementioned K ¹ substituents are dimethyl carbonate, diethyl carbonate, dipropyl carbonate (isomers), diallyl carbonate, dibutenyl carbonate (isomers), dibutyl carbonate (isomers), diphenyl carbonate (isomers), diheptyl isomers) , dinonyl carbonate (isomers), didecyl carbonate (isomers), dicyclopentyl carbonate, dicyclohexyl carbonate, dicycloheptyl carbonate, dibenzyl carbonate, diphenethyl carbonate (isomers), di (phenylpropyl) carbonate (isomers), di (phenylbenbyl) nat (isomers), di (chlorobenzyl) carbonate (isomers), di (methoxybenzyl) carbonate (isomers), di (methoxymethyl) carbonate, di (methoxyethyl) carbonate (isomers), di (chloroethyl) carbonate (isomers) and di (cyanoethyl) ) carbonate (isomers).

Of the above dialkyl carbonates, dialkyl carbonates preferably used in the present invention are dialkyl carbonates in which K ¹ represents an alkyl group containing not more than four carbon atoms and not containing a halogen atom. A particularly preferred dialkyl carbonate is dimethyl carbonate. In addition, of the preferred dialkyl carbonates, dialkyl carbonates obtained in a state where substantially no halogen is present, for example dialkyl carbonates derived from a substantially halogen-free alkenyl carbonate and a substantially halogen-free alcohol, are particularly preferred.

The aromatic monohydroxy compound used in the present invention is a compound represented by the general formula (23). The type of aromatic monohydroxy compound is not limited as long as the hydroxyl group is directly bonded to the aromatic group:

Ar ¹ OH (23), where Ar ¹ is an aromatic group containing from 5 to 30 carbon atoms. Examples of aromatic monohydroxy compounds containing such Ag ¹ are phenol; various alkyl phenols, such as cresol (isomers), xylene (isomers), trimethyl phenol (isomers), tetramethyl phenol (isomers), ethyl phenol (isomers), propyl phenol (isomers), butyl phenol (isomers), diethyl phenol (isomers) methylpropylphenol (isomers), dipropylphenol (isomers), methylbutylphenol (isomers), pentylphenol (isomers), hexylphenol (isomers) and cyclohexylphenol (isomers); various alkoxyphenols such as methoxyphenol (isomers) and ethoxyphenol (isomers); arylalkylphenols such as phenylpropylphenol (isomers); naphthol (isomers) and various substituted naphthols; and heteroaromatic monohydroxy compounds such as hydroxypyridine (isomers), hydroxycoumarin (isomers) and hydroxyquinoline (isomers). Of these aromatic monohydroxy compounds, unsubstituted phenol and substituted phenols in which Ar ¹ represents an aromatic group containing from 6 to 10 carbon atoms are preferred for use in the present invention. Unsubstituted phenol is particularly preferred. In addition, of the aromatic monohydroxy compounds, monohydroxy compounds substantially free of halogen are preferred for use in the present invention.

The molar ratio of the dialkyl carbonate to the aromatic monohydroxy compound used in the case of obtaining a reaction mixture containing an alkyl aryl carbonate, which is the starting material in the present invention, should be in the range from 0.1 to 10. Outside of this range, the amount of unreacted material remaining comparable with the required amount of alkyl aryl carbonate , strives to become large, which is inefficient, and, in addition, it takes a lot of energy to release this unreacted roving material. For these reasons, the above molar ratio is preferably in the range from 0.5 to 5, more preferably from 1 to 3.

The catalyst used in the present invention is a homogeneous catalyst that contains metals such as Pb, Cu, Ζη, Her, Co, N1, A1, Τι, V, 8p and others, and which dissolves in the reaction system. Therefore, a catalyst may preferably be used in which the aforementioned metal component is bound to organic groups. The catalyst component, of course, can react with an organic compound present in the reaction system, such as aliphatic alcohols, aromatic monohydroxy compounds, alkyl phenol carbonates, diphenyl carbonates and dialkyl carbonates, or it can be heat treated with the starting material or products before the reaction. The catalyst used in the present invention is preferably a catalyst that has high solubility in the reaction liquid under reaction conditions. Examples of preferred catalysts from this point of view are PbO, Pb (OH) 2, and Pb (OP11). <T1C1 ₄ , T1 (OMe) ₄ , (MeO) T1 (ORb) 3, (MeOtKORCT. (MeO) 3T1 (ORy) and T1 (ORy) ₄ ; 8pS1 ₄ , 8p (ORy) ₄ , Vi ₂ 8pO and Vi ₂ 8p (ORy) ₂ ; HerS1 ₃ , Her (OH) ₃ and Her (ORy) ₃ ; and such catalysts that were processed aromatic monohydroxy compounds, reaction liquid, etc.

In the present invention, it is particularly preferred to use a starting material and a catalyst that do not contain halogen. In this case, the diaryl carbonate produced does not contain halo.

- 7 011827 gene in general, and therefore, is of importance as a raw material in the industrial production of polycarbonate by: a transesterification method. The reason is the fact that if the halogen is present in the polymerization feed even in an amount of less than, for example, 1 ppm, then this halogen inhibits the polymerization reaction, causes a deterioration in the properties of the produced polycarbonate and causes a color change of the polycarbonate.

The reaction mixture containing an alkyl aryl carbonate is produced by a transesterification reaction between a dialkyl carbonate and an aromatic monohydroxy compound (Formula 24):

KZOSOOK ¹ + Ar ¹ OH AgOSOOK + KO11 (24).

The method for producing a reaction mixture containing an alkyl aryl carbonate can be any method, but a particularly preferred method for industrial implementation is a method in which a continuously multi-stage distillation column is used as a reaction distillation column, as previously proposed by the applicants of the present invention. Particularly preferred in this way is a method in which the transesterification reaction between a dialkyl carbonate and an aromatic monohydroxy compound is carried out in the presence of a homogeneous catalyst, and the reaction mixture containing alcohol is continuously withdrawn from the top of the column, while the reaction mixture containing alkylaryl carbonate is continuously withdrawn from the bottom of the column.

In the present invention, the alkylaryl carbonate-containing reaction mixture obtained by the above process is continuously fed to the reaction distillation column, which is a continuously operating multi-stage distillation column in which a homogeneous catalyst is present; the transesterification and distillation reaction takes place simultaneously in the column, the low boiling point reaction mixture containing the produced dialkyl carbonate is continuously withdrawn from the top of the column in gaseous form, and the high boiling point reaction mixture containing the diaryl carbonate is continuously withdrawn from the bottom of the column in liquid form. The transesterification reaction means a reaction in which the alkoxy group of an alkyl aryl carbonate is exchanged with an aryloxy group of an aromatic monohydroxy compound present in the system and the alcohol is cleaved (formula 25), and a reaction in which two alkyl aryl carbonate molecules are converted to a diaryl carbonate and a dialkyl carbonate between them, i.e. disproportionation (formula 26). In the reaction distillation column of the present invention, a disproportionation reaction of an alkyl aryl carbonate generally proceeds.

Ag'OSOOK ¹ + Ar ¹ OH Ar ¹ OSOOAg ¹ + K ¹ OH (25)

2AgOSOOK Ag ¹ OSOOAg ¹ + KOSOOK (26)

It should be noted that the reaction mixture containing alkylaryl carbonate used as starting material in the present invention may be of high purity or may contain other compounds, for example, the reaction mixture may contain dialkyl carbonate and / or aromatic monohydroxy compound used to produce alkylaryl carbonate, or may contain compounds or reaction by-products produced in this process and / or in other processes, for example, alcohols, alkylaryl ethers, diaryl carbonates, by-products intermediate products with intermediate boiling points and / or high boiling point by-products. A method in which a reaction mixture obtained by transesterification between a dialkyl carbonate and an aromatic monohydroxy compound is used as it is, as starting material in the present invention without unreacted materials and with the catalyst separated from it, is also preferred. In addition, in the case of industrial implementation, as in the present invention, as the dialkyl carbonate and aromatic monohydroxy compound used to obtain the reaction mixture containing alkylaryl carbonate, which is taken as the starting material in the present invention, in addition to fresh dialkyl carbonate and aromatic monohydroxy compound newly introduced into the reaction system, it is also preferable to use a dialkyl carbonate and aromatic monohydroxy compound isolated from this process or from others ogih processes.

The reaction distillation column used in the present invention preferably has a specific structure. That is, the reaction distillation column must be designed to satisfy various conditions, so that in the method of the present invention it is possible to carry out not only distillation, but also at the same time a reaction in order to be able to produce a high boiling point reaction mixture containing diaryl carbonate in an amount capable of providing at least 1 t / h of high purity diaryl carbonate for an extended period of time. That is, the reaction distillation column satisfies not only the conditions in terms of the distillation function, but, moreover, these conditions are combined with the conditions required in order to obtain a reaction that proceeds stably and with high selectivity. More specifically, the reaction distillation column is preferably a continuously operating multi-stage distillation column having a length b (cm), an inner diameter Ό (cm) and internal elements with the number of steps n in them, and, in addition, having a gas outlet with an inner diameter f (cm) at the top of the column or in the upper part of the column near its top, liquid outlet with an inner diameter of ά ₂ (cm) in the bottom of the column or in the lower part of the column near the bottom at least one inlet equipped

- 8 011827 of the upper part and / or in the middle part of the column below the gas outlet, and at least one inlet equipped in the lower part of the column above the liquid outlet, where b, Ό, η, άι and ά ₂ satisfy the following formulas (10) - (fifteen):

1500 <b <8000 (10) 100 <Ό <2000 (eleven) 2 <Ε / Ό <40 (12) 10 <η <83 (thirteen) 2 <Ό / ά1 <15 (14) 5 <Ό / ά ₂ <30 (fifteen).

It should be noted that the definition “at the top of the column near its top” refers to a position extending downward from the top of the column to a position corresponding to approximately 0.25b, and the definition “at the bottom of the column near its bottom” refers to a position that extends upward from the bottom of the column to a position corresponding to approximately 0.25b. The value of b is defined above.

It was found that when using a continuously operating multi-stage distillation column, which simultaneously satisfies formulas (10) - (15), a high-boiling reaction mixture containing diaryl carbonate as the main component can be obtained from a reaction mixture containing alkyl aryl carbonate with high selectivity and high productivity stable over a long period of time, for example, for at least 2000 hours, preferably at least 3000 hours, more preferably at least 5000 hours, per count a quantity ensuring the production of high-purity diaryl carbonate on an industrial scale of not less than 1 t / h. Although the reason why it becomes possible to produce diaryl carbonate on an industrial scale with such excellent results due to the implementation of the process of the present invention is not clear, it is believed that this is due to the combined effect created when the conditions of formulas (10) to (15) are combined. Preferred ranges for the respective factors are described below.

If b (cm) is less than 1500, the conversion drops and it is not possible to achieve the desired performance. In addition, in order to restrain the growth of equipment costs while maintaining the conversion that ensures the desired performance, b should be no more than 8000. More preferably, the interval for b (cm) is 2000 <b <6000, and even more preferably 2500 <b <5000.

If Ό (cm) is less than 100, it is not possible to achieve the desired performance. In addition, in order to restrain the growth in the cost of equipment when achieving the desired performance, Ό should be no more than 2000. More preferably, the interval for Ό (cm) is 150 <Ό <1000, and even more preferably 200 <b <800.

If the ratio b / b is less than 2 or more than 40, stable operation becomes problematic. In particular, if the b / b ratio is greater than 40, the pressure difference between the top and bottom of the column becomes too large, and therefore, long-term stable operation becomes problematic. In addition, there is a need to increase the temperature in the lower part of the column, and, therefore, side reactions become more possible, which causes a decrease in selectivity. A more preferred range for the b / b ratio is 3 <b / n <30, with even more preferably 5 <b / n <15.

If η is less than 10, the conversion drops and it is not possible to achieve the desired performance. In addition, to restrain the growth of equipment costs while maintaining the conversion that ensures the desired performance, η should be no more than 80. In addition, if η is greater than 80, the pressure difference between the top and bottom of the column becomes too large, and, therefore, long-term stable work becomes problematic. Moreover, there is a need to increase the temperature in the lower part of the column, and, therefore, side reactions become more possible, which causes a decrease in selectivity. A more preferred range for η is 15 <η <60, with even more preferably 20 <η <50.

If Ό / άι is less than 2, the cost of equipment becomes high. In addition, large amounts of gaseous components are easily released to the outside of the system, and therefore, stable operation becomes problematic. If Ό / άι is less than 15, the amount of the gaseous component discharged becomes relatively low, and therefore, stable operation becomes problematic, and furthermore, it causes a decrease in the reaction constant. A more preferred range for Ό / άι is 2.5 <Ό / άι <12, with even more preferably 3 <Ό / ά1 <10.

If Ό / ά ₂ is less than 5, the cost of equipment becomes high. In addition, the amount of liquid discharged becomes relatively high, and therefore, stable operation becomes problematic. If Ό / ά ₂ is greater than 30, the flow rate through the fluid outlet and the piping system becomes extremely fast, and therefore, the possibility of erosion causing corrosion of the equipment increases. A more preferred interval for Ό / ά ₂ is

- 9 011827

7 <Ό / ά ₂ <25, with even more preferably 9 <Ό / ά ₂ <20.

The definition of "long-term stable operation" used in the present invention means that the work can be carried out continuously in a stationary state based on operating conditions without clogging the piping system, erosion or distillation process disturbances, such as flooding, for at least 1000 hours, preferably not less than 3000 hours, more preferably not less than 5000 hours; and the prescribed amount of diaryl carbonate can be obtained while maintaining high selectivity.

The "selectivity" for diaryl carbonate during the reaction distillation process in the present invention is calculated based on the reacted alkyl aryl carbonate. In the present invention, a high selectivity of at least 95%, more preferably at least 99%, can usually be achieved.

The continuously operating multi-stage distillation column used as a reaction distillation column in the present invention is preferably a distillation column having a plate and / or packing as internal elements. The definition of "internal elements" in the present invention means elements in a distillation column, where the gas and liquid actually come into contact with each other. As a plate, for example, a cap plate, a mesh plate, a valve plate, a countercurrent plate, a 8regregas plate, a MahGgas plate, etc. are preferred. Non-standard nozzles such as Rashig ring, Lessing ring, Pell ring, Berl nozzle, Intalox saddle, Dixon nozzle, McMagon nozzle or He11-Cancer, or structured nozzles such as Me11arak, Oeshrak, TESNIO-RAK are preferred. , E1ekh1ras, nozzle 8ikag, nozzle OobgoI or nozzle C1йс1щпб. It should be noted that the definition of "number of steps (n) in the form of internal elements" used in the present invention means the total number of plates in the case of a plate and the theoretical number of stages in the case of a nozzle. Thus, in the case of a multi-stage column having both a plate part and a part filled with a nozzle, n means the sum of the total number of plates and the theoretical number of stages of the nozzle.

The reaction between the alkyl aryl carbonate and the aromatic monohydroxy compound present in the system has an extremely low equilibrium constant, and furthermore, the reaction rate is slow. In addition, the disproportionation reaction of alkylaryl carbonate, which is the main reaction, also represents an equilibrium reaction and has a low equilibrium constant and a slow reaction rate. It has been found that a multi-stage distillation column having both a packing and a plate as internal elements is preferred as a continuously operating multi-stage distillation column used in reaction distillation to carry out the above reactions in the present invention. Preferably, such a distillation column has a portion packed with a nozzle located in the upper part of the distillation column and a plate part mounted in the lower part of the distillation column. In addition, in the present invention, the nozzle is preferably a structured nozzle, and it is also preferable to use one or many sets thereof.

The structured nozzle is preferably at least one type of nozzle selected from Me11arak, Oeshrak, TESNIO-RAK, E1ekh1ras, 8ikag nozzles, Soobgo11 nozzles or C1ys1shpb nozzles.

In addition, it has been found that for the reaction distillation column in the present invention, a mesh plate having a mesh portion and an overflow portion is particularly effective as a tray of internal elements in terms of the relationship between productivity and equipment cost. It has also been found that the mesh nozzle preferably has 100 to 1000 holes / m ² in the mesh portion. More preferably, the number of holes is from 120 to 900 holes / m ² , even more preferably from 150 to 800 holes / m ² . In addition, it was found that the cross-sectional area of one hole of the mesh plate is preferably in the range from 0.5 to 5 cm ² . More preferably, the cross-sectional area of one hole is from 0.7 to 4 cm ² , even more preferably from 0.9 to 3 cm ² . Moreover, it has been found that it is particularly preferable if the mesh plate has from 100 to 1000 holes / m ² in the mesh portion, and the cross-sectional area of one hole is in the range from 0.5 to 5 cm ² . In addition, it has been found that it is particularly preferable if the structured nozzle is at least one type of nozzle selected from Me11arak, Oeshrak, TESNIO-RAK, E1ekh1ras, 8i1 / ar nozzles, OobgoI nozzles or OShsidp nozzles, and a mesh plate has from 100 to 1000 holes / m ² in the mesh part and the cross-sectional area of one hole is in the range from 0.5 to 5 cm ² .

It is shown that by adding the above conditions to the reaction distillation column, the reaction distillation process in the present invention can be carried out more easily.

When carrying out the reaction distillation process in the present invention, the diaryl carbonate is produced continuously by continuously feeding the starting material containing the alkyl aryl carbonate to a continuously operating multi-stage distillation column in which a homogeneous catalyst is present, simultaneously conducting the reaction and distillation in the column, continuously discharging the low boiling point reaction mixture containing dialkyl carbonate and alcohol, from the top

- 10 011827 columns in gaseous form, and continuous withdrawal of a high boiling point reaction mixture containing diaryl carbonate as the main reaction product from the bottom of the column in liquid form. In the present invention, the method of preparing the catalyst that is present in the reaction distillation column can be any method, but since the catalyst is a homogeneous catalyst that is soluble in the starting material or in the reaction liquid, it is preferable to feed the catalyst to the distillation column from a position above the middle part of the distillation the columns. In this case, the catalytic liquid dissolved in the starting material or in the reaction mixture may be introduced into the column together with the starting material, or may be introduced into the column from another input into the starting material. In addition, the catalyst in the starting material containing alkylaryl carbonate, which is used in the production of the specified starting material, can also preferably be taken, as it is, as a catalyst in the reaction distillation process under consideration; in this case, fresh catalyst can be added as needed. The amount of catalyst used in the present invention varies depending on the type of catalyst, types and proportions of the starting material compounds and reaction conditions, such as reaction temperature and reaction pressure. The amount of catalyst is usually in the range from 0.0001 to 30 wt.%, Preferably from 0.005 to 10 wt.%, More preferably from 0.001 to 1 wt.% Based on the total weight of the starting material.

The low boiling point reaction mixture continuously discharged from the top of the reaction distillation column may contain an alkyl aryl ether and an aromatic monohydroxy compound present in the system, unreacted alkyl aryl carbonate, etc. Such a low boiling point reaction mixture is preferably recycled to a reactor in which the transesterification reaction between the dialkyl carbonate and aromatic monohydroxy compound is carried out.

In addition, in the present invention, a method is preferred in which a condensable gaseous component withdrawn from the top of the reaction distillation column is irrigated, and then some of this component is returned to the top of the distillation column. In this case, the reflux ratio is usually from 0.05 to 10, preferably from 0.08 to 5, more preferably from 0.1 to 2.

In the present invention, when the starting material containing alkylaryl carbonate is continuously fed to the reaction distillation column, such starting material is preferably fed to the reaction distillation column in liquid and / or gaseous form from the inlet (s) equipped in one or in many positions at the top or middle of the column below the gas outlet at the top of the distillation column. In addition, in the case of using a distillation column having a nozzle in its upper part and a plate in its lower part, which is the preferred embodiment of the present invention, it is preferable that at least one position where the inlet is equipped is located between the nozzle part and the plate part . Moreover, in the case where the nozzle includes many sets of structured nozzles, a method in which the input is installed in the space between the sets of structured nozzles is preferred.

The reaction time in the case of the transesterification reaction carried out in the present invention is considered equal to the average residence time of the reaction liquid in the reaction distillation column. The reaction time varies depending on the type of internal element of the distillation column and the number of stages, the amount of starting material supplied to the column, the type and amount of catalyst, reaction conditions, etc. The reaction time is usually in the range from 0.01 to 10 hours, preferably from 0.05 to 5 hours, more preferably from 0.1 to 3 hours.

The reaction temperature varies depending on the type of starting material compounds used and the type and amount of catalyst. The reaction temperature is usually in the range from 100 to 350 ° C. It is preferable to increase the reaction temperature in order to increase the reaction rate. However, if the reaction temperature is too high, side reactions become noticeable, for example, the formation of by-products, such as Fris rearrangement products of diaryl carbonate and alkylaryl ether, and the number of ester compounds increases, which is undesirable. For this reason, the reaction temperature is preferably in the range from 130 to 280 ° C., more preferably from 150 to 260 ° C., even more preferably from 180 to 240 ° C. In addition, the reaction pressure varies depending on the type of starting material compounds and the composition of the starting material, reaction temperature, etc. The reaction pressure may be any reduced pressure, normal pressure, or applied pressure. The pressure at the top of the column is usually in the range from 0.1 to 2x10 ⁷ Pa, preferably from 10 ³ to 10 ⁶ Pa, more preferably from 5x10 ³ to 10 ⁵ Pa.

In the present invention, the high boiling point reaction mixture containing diaryl carbonate continuously discharged from the bottom of the reaction distillation column, typically, in addition to the diaryl carbonate, contains a catalyst, dialkyl carbonate, alkyl aryl ether, aromatic monohydroxy compound, alkyl aryl carbonate, by-products, etc. In addition, the high boiling point reaction mixture typically contains small amounts of other impurities and by-products of the reaction, for example an intermediate boiling material having a boiling point between the boiling point

- 11 011827 alkylaryl carbonate and the boiling point of diaryl carbonate, such as cresol, alkoxycarbonyl (hydroxy) arene (e.g. methyl salicylate), alkyl (alkylaryl) carbonate (e.g. methyl cresyl carbonate), alkoxycarbonyl (alkoxycarboxyl) arene (e.g. methylmethoxybenzo) carbonate (e.g. methoxyethyl phenyl carbonate) and alkyl aryl ethers (e.g. cresyl phenyl ether) and a high boiling point material having a boiling point higher than the boiling point of a diaryl carbonate such as aryloxycarbonyl (hydroxy) arene (e.g. ep, phenyl salicylate), alkoxycarbonyl (aryloxy) arene (e.g. methyl phenoxybenzoate), alkylaryl aryl carbonate (e.g. cresyl phenyl carbonate), xanton and substituted xanthones, aryloxycarbonyl (alkoxy) arene (e.g. phenylmethoxybenzoate) aryl, aryl, aryloxycarbonyl (aryloxycarbonyl) arenes (e.g. 1-phenoxycarbonyl-2-phenoxycarboxyphenylene).

The compounds in parentheses for the intermediate boiling material and the high boiling material described above are compounds that may be present in the high boiling point mixture containing diphenyl carbonate continuously discharged from the bottom of the reaction distillation column if the reaction material is used as starting material a mixture containing methyl phenyl carbonate obtained by the transesterification reaction between dimethyl carbonate and phenol. In addition, the reason for the formation of a compound containing an alkoxyethyl group is not clear, but this may be due to 2-alkoxyethanol and / or 2 alkoxyethylalkyl carbonate present in small amounts in the dialkyl carbonate obtained as a by-product in the case where the dialkyl carbonate is obtained from ethylene carbonate and alcohol.

However, the high boiling point by-products described above can be difficult to separate, and using the processes proposed to date, it was not possible to reduce the amount of such high boiling point by-products to a sufficient level. Moreover, with regard to by-products with intermediate boiling points, the documents to date do not even mention their existence, and, therefore, there are no documents that in any way reveal or suggest the separation process, and therefore the removal such by-products with intermediate boiling points. In the production of diaryl carbonate from dialkyl carbonate and aromatic monohydroxy compounds, the applicants of the present invention carried out a continuous continuous operation with recirculation and, therefore, with reuse of the starting material, and as a result found that the material with an intermediate boiling point and high boiling material described above are formed as by-products and accumulate over time in the system. The applicants of the present invention also found that if a diaryl carbonate, for which the amounts of such an intermediate boiling material and high boiling point material were not reduced to a sufficient level, is used as a raw material for the method of producing polycarbonate by transesterification, this material will cause a color change and deterioration . Accordingly, an effective process is required to reduce the quantities of both by-products with intermediate boiling points and high boiling point by-products to a sufficient level. The method of the present invention achieves its goal.

In the present invention, the following should be carried out: a high boiling point reaction mixture containing diaryl carbonate continuously discharged from the bottom of the reaction distillation column (a) is continuously introduced into the separation column of the high boiling material A and continuously subjected to distillation separation into the upper product from the column (A _T ) containing diaryl carbonate, and the bottom product from the column (A _c ) containing a catalyst and high boiling material;

(b) the top product from the column (A _t ) is continuously introduced into the purification column of diaryl carbonate B having a lateral overhead output and is continuously subjected to distillation separation into the upper product from the column (B _t ), the product discharged from the side of the column (B ₃ ) and the bottom product from the column (B _c ), wherein high purity diaryl carbonate is continuously withdrawn as a product discharged to the side of the column (B ₃ ); and (c) the top product from the column ( _Bt ) is continuously introduced into the material separation column with an intermediate boiling point C having a side stream output and is continuously subjected to distillation separation into the upper product from the column (C _t ) containing alkylaryl carbonate as the main component , product withdrawn sideways of the column _(C3) comprising as a main component material having an intermediate boiling point, having a boiling point between the boiling point of the alkyl aryl carbonate and the boiling temperature diarilkarb nata and a bottom product from column (St), containing a diaryl carbonate as a main component.

A characteristic feature of the present invention is that the processes described above (a), (b) and (c) are carried out in this order. This is due to the fact that during these processes in the indicated order, the thermal history of dialkyl carbonate can be minimized, and, as a result, side reactions of diaryl carbonate can be suppressed. Regarding the process described in patent document 17, in which the distillation separation is carried out using three columns described

- 12 011827 and the diaryl carbonate is obtained from the top of the third column, then the thermal background of the diaryl carbonate is large. In the present invention, more preferably the following:

(b) the top product from the column (C _t ) is continuously fed to the reaction distillation column; and / or (e) the bottom product from the column (C _B ) is continuously fed into the high-boiling material separation column (A).

When carrying out the process (s) (b) and / or (e) for recycling and, consequently, reusing the top product from the column (C _t ) and / or the bottom product from the column (C _B ), high purity diaryl carbonate performance can be improved , which is of great importance in industrial implementation.

In the present invention, at least 1 t / h of high-purity diaryl carbonate is produced continuously as a product discharged to the side of the column (B ₈ ) from the diaryl carbonate B purification column. For these purposes, the high-boiling material separation column A, the diaryl carbonate purification column B and the intermediate material separation column the boiling point C should be a continuously operating multi-stage distillation column containing a certain structure, and should be used in combination with each other in the manner described by you e.

The separation column of the high-boiling material A should be a continuously operating multi-stage distillation column having a length of b _A (cm), an inner diameter of Ό _Α (cm) and internal elements with the number of steps in them _{А A} , where b _A , Ό _Α and _{А A} satisfy the following formulas (1) - (3):

800 <b _a <3000 (one), 100 <Ό _α <1000 (2) 20 <n _a <100 (3).

The inner element is preferably a plate and / or nozzle as described above.

It is undesirable for L _A (cm) to be less than 800, since the height at which the internal element can be mounted becomes limited, and therefore, the separation efficiency decreases. In addition, in order to restrain the growth in the cost of equipment when achieving the desired separation efficiency, _A should be no more than 3000. A range of values of _A (cm) 1000 <b _a <2500 is more preferable, and even more preferably 1200 <b _A <2000.

If Ό _Α (st) is less than 100, it is not possible to achieve the desired performance. In addition, to restrain the growth of equipment costs when achieving the desired performance, Ό _Α should be no more than 1000. More preferably, the range of values for Ό _Α (cm) is 200 <Ό _α <600, and even more preferably 250 <Ό _α <450.

If n _A is less than 20, the separation efficiency decreases, and therefore, the required purity cannot be achieved. In addition, to curb the rising cost of equipment while achieving the desired separation efficiency, n _A must be not more than 100. Furthermore, if nA is greater than 100, the pressure difference between the top and bottom of the column becomes too great, and hence prolonged stable operation separation columns of high boiling material A becomes problematic. Moreover, it becomes necessary to increase the temperature in the lower part of the column, and therefore side reactions become more likely, which is undesirable. More preferable is the range of values for p _A 30 <p _a <70, with even more preferably 35 <p _a <60.

The distillation conditions in the case of the separation column of high boiling material A preferably correspond to a temperature at the bottom of the column T _A in the range from 185 to 280 and a pressure at the top of the column P _A in the range from 1000 to 20,000 Pa.

It is undesirable for T _{A to} be lower than 185 ° C, since as a result the pressure at the top of the column may drop, and, therefore, it will be necessary to use equipment to maintain: high vacuum; In addition, equipment is growing in size. In addition, it is undesirable for T _{A to} be higher than 280 ° C, since, as a result, high boiling point by-products are formed during the distillation. A more preferable range for the values for T _A is from 190 to 240 ° C., even more preferably from 195 to 230 ° C.

It is undesirable for the RA to be below 1000 Pa, since in this case it is necessary to use large equipment that can maintain a high vacuum. In addition, it is undesirable for the RA to be lower than 20,000 Pa, since in this case the distillation temperature must be increased, and therefore, the formation of by-products increases. More preferably, the range of RA is from 2000 to 15000 Pa, and even more preferably from 3000 to 13000 Pa.

In addition, the reflux ratio for the high boiling material separation column A is usually in the range from 0.01 to 10, preferably from 0.08 to 5, more preferably from 0.1 to 3.

The diaryl carbonate B purification column shall be a continuously operating multi-stage distillation column having a length of B _B (cm), an inner diameter of Ό _Β (cm) and internal

- 13 011827 elements with the number of steps in them p _in , where b _in , B _in and p _in satisfy the following formulas (4) - (6):

1000 <b _at <5000 (4), 100 <P _to <1000 (5), 20 <pv <70 (6).

The inner element is preferably a plate and / or nozzle as described above.

In addition, the diaryl carbonate purification column B is preferably a continuously operating multi-stage distillation column having an input b1 in the middle of the column and a side stream output B2 between the input b1 and the bottom of the column and having the number of stages p ₁ in the form

of internal elements above input b1, the number of steps n2 in the form of internal elements between input b1 and the output of the side shoulder strap and the number of steps n3 in the form of internal elements below the output of the side shoulder B2, and the total number of stages (n + n ₂ + n ₃ ) is equal to n _in where n ₁ , n ₂ and n ₃ satisfy the following formulas (16) - (18): 5 <n1 <20 (sixteen), 12 <n2 <40 (17) 3 <n3 <15 (eighteen).

It is undesirable for b _in (cm) to be less than 1000, since the height at which the internal elements can be installed becomes limited, and therefore, the separation efficiency decreases. In addition, in order to restrain the growth in the cost of equipment when achieving the desired separation efficiency, b _in should be no more than 5000. It is more preferable that the interval of values of b _in (cm) 1500 <b _in <3000, and even more preferably 1700 <b _in <2500.

If B |; (cm) is less than 100, it is impossible to achieve the desired performance. In addition, to restrain the growth in the cost of equipment while achieving the desired performance B |; should be no more than 1000. More preferably, the range of values for B _in (cm) is 150 <B |, <500. even more preferably 200 <Ό _Α <400.

If n _in is less than 20, then the separation efficiency for the column as a whole decreases, and therefore, the required purity cannot be achieved. In addition, to restrain the growth of equipment costs while achieving the desired separation efficiency, the PV should be no more than 70. In addition, if the PV is more than 70, then the pressure difference between the top and bottom of the column becomes too large, and therefore, long-term stable the operation of the diaryl carbonate purification column B becomes problematic. Moreover, it becomes necessary to increase the temperature in the lower part of the column, and therefore side reactions become more likely, which is undesirable. More preferred is the range of values for n _at 25 <n _at <55, with even more preferably 30 <n _at <50. In addition, to ensure that high purity diaryl carbonate is obtained stably for a long period of time, p ₁ , p ₂ and p ₃ must be in the intervals 5 <p1 <20, 12 <p ₂ <40 and 3 <p ₃ <15, respectively. More preferable ranges are 7 <n1 <15, 12 <f ₂ <30 and 3 <n ₃ <10.

The distillation conditions in the case of the diaryl carbonate purification column B preferably correspond to a temperature at the bottom of column T _in the range of 185 to 280 ° C. and a pressure at the top of column P _in the range of 1000 to 20,000 Pa.

It is undesirable that T _in be below 185 ° C, since, as a result, the pressure at the top of the column may drop, and therefore it will be necessary to use equipment to maintain a high vacuum; In addition, equipment sizes are growing. In addition, it is undesirable that T _in be higher than 280 ° C, since as a result, high-boiling by-products are formed during the distillation. A more preferred range for the values for T _in is the range from 190 to 240 ° C., Even more preferably from 195 to 230 ° C.

It is undesirable for the Pb to be below 1000 Pa, since in this case it is necessary to use large equipment capable of maintaining a high vacuum. Moreover, it is undesirable for the Pb to be lower than 20,000 Pa, since in this case the distillation temperature must be increased, and, consequently, the formation of by-products increases. More preferably, the Pb range is from 2000 to 15000 Pa, even more preferably from 3000 to 13000 Pa.

In addition, the reflux value for the diaryl carbonate purification column B is usually in the range from 0.01 to 10, preferably from 0.1 to 8, more preferably from 0.5 to 5.

The material separation column with an intermediate boiling point C should be a continuously operating multi-stage distillation column having a length of B _C (cm), an internal diameter of B _C (cm) and internal elements with the number of steps in them Hs, where b _C , B _C and n _C satisfy the following formulas (7) - (9):

800 <b _C <3000 (7),

50 <P _C <500 (8),

10 <pC <50 (9).

The inner element is preferably a plate and / or nozzle, which are described

- 14 011827 above.

In addition, the column for separating material with an intermediate boiling point C is preferably a continuously operating multi-stage distillation column having an input C1 in the intermediate stage of the column and an output side stream C2 between the input C1 and the bottom of the column and having the number of steps n ₄ in the form of internal elements above the input C1, the number of stages n _{is 5} in the form of internal elements between the input terminal C1 and C2 and the side stream number of stages p ₆ as internal elements below the side stream withdrawal C2, the total number of stages (n ₄ + n ₅ + n ₆₎ is equal _to n, where n _4, n ₅ and n ₆ satisfy the following formulas (19) - (21):

2 <n4 <15 (nineteen), 5 <n5 <30 (twenty), 3 <n6 <20 (21).

It is undesirable for L _C (cm) to be less than 800, since the height at which the internal elements can be installed becomes limited, and therefore the separation efficiency decreases. In addition, in order to restrain the growth of equipment costs while achieving the desired separation efficiency, b _C should be no more than 3000. A range of values for b _C (cm) 1000 <b _C <2500 is more preferable, and even more preferably 1200 <b _C < 2000.

If E _C (cm) is less than 50, then it is impossible to achieve the desired performance. In addition, in order to restrain the growth in the cost of equipment when achieving the desired performance, E _C should be no more than 500. More preferably, the range of values for E _C (cm) is 80 <Ό,;<300. and even more preferably 100 <E _C <200.

If n _C is less than 10, the separation efficiency for the column as a whole decreases, and therefore the required purity cannot be achieved. In addition, to restrain the growth of the cost of equipment when achieving the desired separation efficiency, n _C should be no more than 50. In addition, if ps is more than 50, the pressure difference between the top and bottom of the column becomes too large, and therefore, long-term stable operation columns separating material with an intermediate boiling point C becomes problematic. Moreover, it becomes necessary to increase the temperature in the lower part of the column, and, therefore, side reactions become more likely, which is undesirable. More preferable is the range of values for p _C 13 <p _C <40, even more preferably 16 <p _C <30. In addition, in order to guarantee the efficiency of separating the material with an intermediate boiling point and to improve the target purity of diaryl carbonate of high purity, preferably n4, n5 and n6 should be in the ranges 2 <I4 <15, 5 <I5 <30 and 3 <n ₆ <20. respectively. More preferred ranges are 3 <n4 <10 7 <n5 <20 and 4 <n ₆ <15.

The distillation conditions in the case of a material separation column with an intermediate boiling point C preferably correspond to a temperature at the bottom of the column T _C in the range from 150 to 280 ° and a pressure at the top of the column P _C in the range from 500 to 18000 Pa.

It is undesirable that T _C be below 150 ° C, since otherwise the pressure at the top of the column may decrease, and therefore it will be necessary to use equipment to maintain a high vacuum, and, in addition, the dimensions of the equipment will increase. In addition, it is undesirable for T _{C to} be higher than 280 ° C, since in this case, high boiling point by-products are formed during the distillation. A more preferred range for the values for TC is the range from 160 to 240 ° C, and even more preferably from 165 to 230 ° C.

It is undesirable that P _C be below 500 Pa, since in this case it is necessary to use large equipment capable of maintaining a high vacuum. In addition, it is undesirable for RS to be below 18,000 Pa, since in this case the distillation temperature should be increased, and, consequently, the formation of by-products increases. More preferably, the range of RS is from 800 to 15000 Pa, and even more preferably from 1000 to 13000 Pa.

In addition, the reflux ratio for a material separation column with an intermediate boiling point C is usually in the range from 0.01 to 10, preferably from 0.1 to 5, more preferably from 0.2 to 2.

It was found that when using a high-boiling material separation column A, a diaryl carbonate purification column B and a material separation column with an intermediate boiling point C, while satisfying all the above conditions, high-purity diaryl carbonate can be obtained on an industrial scale in an amount of not less than 1 t / stably for a long period of time, for example, not less than 2000 hours, preferably not less than 3000 hours, more preferably not less than 5000 hours, from a high boiling point reaction hydrochloric mixture comprising diaryl carbonate. The reason why it becomes possible to produce high purity diaryl carbonate on an industrial scale with such excellent results due to the implementation of the method of the present invention is not clear, but it is believed that this is due to the combined influence of the distillation conditions and the effect that occurs when the conditions of formulas (1) - (9 ) are combined.

In the present invention, a high boiling point reaction mixture continuously discharged from the bottom

- 15 011827 reaction distillation column, preferably fed into the separation column of the high-boiling material A. Such a high-boiling reaction mixture usually contains from 0.05 to 2 wt.% Dialkyl carbonate, from 0.1 to 20 wt.% Aromatic monohydroxy compounds, from 0.02 to 2 wt.% Alkylaryl ether, from 10 to 45 wt.% Alkylaryl carbonate, from 50 to 80 wt.% Diaryl carbonate, from 0.01 to 1 wt.% By-products with intermediate boiling points, from 0.1 to 5 wt.% high boiling point by-products and from 0.001 to 5 wt.% of the catalyst. The composition of the high boiling point reaction mixture varies depending on the conditions of the reaction distillation, the type and amount of catalyst, etc., but as long as the reaction distillation is carried out under constant conditions, a reaction mixture of approximately constant composition can be obtained, and therefore the composition of the high boiling point reaction mixture into the high-boiling material separation column A will be approximately constant. However, while in the present invention the composition of the high boiling point reaction mixture is within the indicated range, even if the composition sometimes changes, the separation can still be carried out with approximately the same separation efficiency. This is one of the characteristic features of the present invention.

In the present invention, when a high boiling point reaction mixture is continuously supplied to the high boiling material separation column A, the high boiling point reaction mixture may be supplied in the form of liquid from the inlet (s) equipped at one or a plurality of positions below the middle of the separation column A, or also preferably supply a high-boiling reaction mixture to the column through the reboiler of the separation column A from the piping system equipped at the bottom of the reboiler. The amount of high boiling point reaction mixture supplied to the separation column of high boiling material A varies depending on the amount of diaryl carbonate to be produced, the concentration of diaryl carbonate in the high boiling point mixture, separation conditions in separation column A, etc. The high boiling point reaction mixture used in the present invention typically contains from 50 to 80% by weight of diaryl carbonate, and therefore, to obtain at least 1 t / h of high purity diaryl carbonate, regardless of the content of the diaryl carbonate, the amount of high boiling point reaction mixture continuously introduced in the separation column of the high-boiling material A, is not less than about 1.3 to 2 t / h, but not more than 100 t / h. The indicated amount is usually not less than about 2 t / h, preferably not less than about 6 t / h, more preferably not less than about 10 t / h. The upper limit of the indicated quantity varies depending on the size of the installation, the required capacity, etc., but usually is 200 t / h.

The high boiling point reaction mixture continuously fed into the high boiling material separation column A is separated into the top product from the column (A _t ) containing most of the diaryl carbonate, most of the compounds having a lower boiling point than the boiling point of the diaryl carbonate, such as unreacted starting material, alkylaryl ether, alkylaryl carbonate and an intermediate boiling material, and a very small amount of high boiling point by-products, and to the bottom product from the column (A _c ), with containing a small amount of diaryl carbonate, a catalyst and most of the by-products having a higher boiling point than the boiling point of diaryl carbonate. The bottom product from the column (A _c ) may contain small amounts of aromatic monohydroxy compound, alkyl aryl carbonate and by-products with intermediate boiling points. Such organic materials in the bottom product from the column (AB) play a useful role in the dissolution of the catalyst component, and, therefore, to maintain a liquid state. It is usually preferred that all or some of the bottom product from column (Av) is recycled to a reactor in which the transesterification reaction between the dialkyl carbonate and aromatic monohydroxy compound and / or the reaction distillation column of the present invention is carried out as a catalytic component of the transesterification reaction.

In the present invention, it is particularly preferable to produce unsubstituted diphenyl carbonate or diphenyl carbonate substituted with a lower hydrocarbon group by using unsubstituted phenol or phenol substituted with a lower hydrocarbon group as an aromatic monohydroxy compound. In this case, the catalyst component and by-products having a higher boiling point than the boiling point of diphenyl carbonate, such as phenyl salicylate, xanthon, phenylalkoxybenzoate and 1-phenoxycarbonyl-2-phenoxycarboxyphenylene, or by-products having a higher boiling point than substituted lower hydrocarbon a diphenyl carbonate group, such as derivatives of the compounds described above substituted by a lower hydrocarbon group, are almost completely separated as the lower product from the column (Ab) into High-boiling material separation A.

A characteristic feature of the present invention is that it is easy to ensure that the content of the catalyst component and by-products having a higher boiling point than the boiling point of diaryl carbonate in the column top product (A _t ) is usually not more than 200 ppm preferably not more than 100 ppm, more preferably not more than 50 ppm. Another characteristic of the present invention is that, despite the fact that

- 16 011827 the top product from the column (A _T ) hardly contains any of the aforementioned high boiling point by-products; most of the introduced diaryl carbonate in the reaction mixture can be removed from the top of the column. In the present invention, not less than 95%, preferably not less than 96%, more preferably not less than 98% of the diaryl carbonate in the reaction mixture continuously fed to the high-boiling material separation column A can be withdrawn from the top of the column.

In addition, in the present invention, regardless of the composition of the reaction mixture supplied to the separation column A, a total of 90 to 97% by weight of the liquid fed continuously is discharged from the top of the column as a top product from the column (AT), wherein from 10 to 3 wt.% continuously removed from the bottom of the column in the form of a lower product from the column (A _in ). The composition of the top product from the column (A _T ) usually corresponds to from 0.05 to 2 wt.% Dialkyl carbonate, from 1 to 21 wt.% Aromatic monohydroxy compound, from 0.05 to 2 wt.% Alkylaryl ether, from 11 to 47 wt. % alkylaryl carbonate, from 0.05 to 1 wt.% by-products with intermediate boiling points and from 52 to 84 wt.% diaryl carbonate; the content of high boiling point by-products is usually not more than 200 ppm, preferably not more than 100 ppm, more preferably not more than 50 ppm.

As indicated above, the amount of the top product from the column (A _T ) continuously discharged from the top of the separation column of the high boiling material A is typically from about 90 to 97% of the reaction mixture fed to the separation column A. The specified top product from the column (AT) is continuously fed into the diaryl carbonate purifying column B from the input equipped in the middle of purification column B, and continuously separated into three products, i.e. the top product from column (B _T) product withdrawn column side (in ₈₎ and a bottom product of the columns s _(B). All of these products having a lower boiling point than the boiling point of the diaryl carbonate contained in the top product from the column (AT) from the separation column A to the purification column B are continuously withdrawn from the top of the purification column as the top product from the column (BT) and a small amount of liquid is continuously withdrawn from the bottom of the purification column B. A small amount of diaryl carbonate is contained in the top product from the column (in _T ), and this amount is usually from 1 to 9%, preferably from 3 to 8%, based on diaryl carbonate fed to the column.

The bottom product from column _(B) from the diaryl carbonate purifying column B comprises the diaryl carbonate and a small amount of high-boiling by-products concentrated to approximately a few percent. Another characteristic feature of the present invention is that the amount of diaryl carbonate in the bottom product from the column (s) discharged from the bottom of the purification column B can be kept very low. Typically, this amount is from 0.05 to 0.5% based on the diaryl carbonate fed to the column.

High purity diaryl carbonate is continuously withdrawn from the side stream output of the diaryl carbonate purification column B, the amount usually being 90-98% based on the diaryl carbonate fed to the purification column B. The purity of the diaryl carbonate obtained as a product discharged from the side of the column (B ₃ ) the present invention typically comprises at least 99.9%, preferably at least 99.99%, more preferably at least 99.999%. The content of by-products with intermediate boiling points having a boiling point between the boiling point of alkyl aryl carbonate and the boiling point of diaryl carbonate is not more than 100 ppm, preferably not more than 30 ppm, more preferably not more than 10 ppm , or it may even be possible to obtain a product discharged to the side of the column (B ₈ ), essentially free of such by-products with intermediate boiling points. In addition, the content of high boiling point by-products having a higher boiling point than the boiling point of diaryl carbonate is not more than 100 ppm, preferably not more than 50 ppm, more preferably not more than 10 ppm.

The content of high-boiling impurities in the diaryl carbonate obtained by carrying out the present invention using an alkyl aryl carbonate obtained by transesterification between an alkyl carbonate and a phenol or phenol substituted by a lower hydrocarbon group is not more than 30 ppm, preferably not more than 10 ppm, more preferably not more than 1 ppm in the case of phenyl salicylate or a derivative substituted with a lower hydrocarbon group, not more than 30 ppm, preferably not more than 10 ppm, more than meaning not more than 1 ppm in the case of xanthan, not more than 30 ppm, preferably not more than 10 ppm, more preferably not more than 1 ppm in the case of phenylmethoxybenzoate or its substituted lower hydrocarbon a derivative group, and not more than 30 ppm, preferably not more than 10 ppm, more preferably not more than 5 ppm in the case of 1-phenoxycarbonyl-2-phenoxycarboxyphenylene or a derivative substituted with a lower hydrocarbon group. Moreover, the total content of such high boiling point by-products is not more than 100 ppm, preferably not more than 50 ppm, more preferably not more than 10 ppm.

In addition, the present invention usually uses a starting material and a catalyst that do not contain halogen, and therefore the halogen content of the resulting diaryl carbonate is not more than 0, 1 ppm, preferably not more than 10 ppm, more preferably not more than 1 ppm

- 17 011827

The top product from the column ( _Bt ), continuously discharged from the top of the diaryl carbonate B purification column, is continuously fed into the material separation column with an intermediate boiling point C from the inlet equipped in the middle of the separation column C and is continuously divided into three products, i.e., the upper product from the column (C _t ), product withdrawn from the side of the column (C ₈ ), and the bottom product from the column (C _B ). The composition of the top product from the column ( _Bt ) from the diaryl carbonate B purification column usually corresponds to from 0.5 to 2% by weight of dialkyl carbonate, from 1 to 20% by weight of aromatic monohydroxy compound, from 0.05 to 2% by weight of alkylaryl ether 60 to 95 wt.% Alkylaryl carbonate, from 0.05 to 2 wt.% By-products with intermediate boiling points and from 0.1 to 15 wt.% Diaryl carbonate; the content of high boiling point by-products is usually not more than 500 ppm, preferably not more than 300 ppm.

The amount of the top product from the column (St) from the column of separation of material with an intermediate boiling point C is usually from 80 to 97 wt.% Based on the filed top product from the column (W _t ). The composition of the top product from the column (C _t ) usually corresponds to from 0.1 to 2 wt.% Dialkyl carbonate, from 1 to 20 wt.% Aromatic monohydroxy compound, from 0.05 to 2 wt.% Alkylaryl ether, from 60 to 95 wt. % alkylaryl carbonate and from 0.05 to 0.5 wt.% by-products with intermediate boiling points; the content of diaryl carbonate and high boiling point by-products is usually not more than 100 ppm, preferably not more than 10 ppm.

The amount of product withdrawn from the side column material separating column intermediate boiling C., usually from 1 to 10 wt.% Based on the fed top product from column (B _t). The composition of the product on the side of the column (Cg) usually corresponds to from 0.01 to 5 wt.% Aromatic monohydroxy compounds, not more than 10 ppm alkylaryl ether, from 10 to 50 wt.% Alkylaryl carbonate, from 10 to 70 wt. % by-products with intermediate boiling points, from 5 to 60% by weight of diaryl carbonate and not more than 1% by weight of high boiling point by-products.

The amount of the bottom product from the column (C _B ) from the material separation column with an intermediate boiling point C is usually from 3 to 15% based on the supplied top product from the column (B _t ). The composition of the bottom product from the column (C _B ) usually corresponds to from 0.01 to 0.5 wt.% Aromatic monohydroxy compounds, not more than 10 ppm alkylaryl ether, from 0 to 3 wt.% Alkylaryl carbonate, from 0 to 0, 1 wt.% By-products with intermediate boiling points, from 95 to 99.9 wt.% Diaryl carbonate and not more than 1 wt.% High-boiling by-products.

It is preferable that some or all of the top product from the column (St) separated by means of a material separation column with an intermediate boiling point C described above is used as a starting material for the initial transesterification reaction and / or for the reaction distillation of the present invention. The column top product (St) has a low content of by-products with intermediate boiling points and high boiling point by-products and has a high alkyl aryl carbonate content, and therefore it is particularly preferred in the present invention to continuously feed the top product from the column (C _t ) to the reaction distillation column, in which the disproportionation reaction proceeds mainly. Such recycling through recycling is especially important in industrial sales.

In addition, it is also preferable to recycle and thus reuse some or all of the bottom product from the column (CB), separated as described above. The bottom product from the column (CB) has a low content of by-products with intermediate boiling points and high boiling point by-products and has a high content of diaryl carbonate, and therefore is preferably released. Although the bottom product from the column (C _B ) can also be continuously fed to the purification column of diaryl carbonate B, it is particularly preferable to continuously feed the bottom product from the column (CB) to the separation column of high boiling material A, since in this case high purity diaryl carbonate can be obtained with still higher performance. Such recycling through recycling is especially important in industrial sales.

The definition of “long-term stable operation” used in the present invention means that the work can be carried out continuously in a stationary mode based on operating conditions without disturbing the reaction, distillation deviations, such as flooding, clogging of the piping system or erosion, for at least less than 1000 hours, preferably not less than 3000 hours, more preferably not less than 5000 hours; and a predetermined amount of high purity diaryl carbonate can be produced while maintaining high selectivity.

In the case of carrying out the present invention using an alkyl aryl carbonate obtained by transesterification between a dialkyl carbonate and a phenol or phenol substituted with a lower hydrocarbon group, the content of by-products with intermediate boiling points in the resulting unsubstituted or substituted lower hydrocarbon group diphenyl carbonate is not more than 100 hours. ppm, preferably not more than 30 ppm, more preferably not more than 10 ppm, even more preferably not more than 1 ppm ppm, and the content of high-boiling impurities is not more than 30 ppm, preferably not more than 10 ppm, more preferably not more than 1 ppm in the case of phenyl salicylate or substituted lower carbohydrate

- 18 011827 a hydrogen derivative group, not more than 30 ppm, preferably not more than 10 ppm, more preferably not more than 1 ppm in the case of xanton, not more than 30 ppm, preferably not more than 10 ppm, more preferably not more than 1 ppm in the case of phenylmethoxybenzoate or a derivative substituted with a lower hydrocarbon group, and not more than 30 ppm, preferably not more than 10 ppm, more preferably not more than 5 ppm in the case of 1 phenoxycarbonyl-2-phenoxycarboxyphenylene or a substituted lower carbohydrate thereof native group derivative. In addition, the total content of these high boiling point by-products is not more than 100 ppm, preferably not more than 50 ppm, more preferably not more than 10 ppm.

In addition, the present invention typically uses dialkyl carbonate, phenol or a phenol substituted with a lower hydrocarbon group and a catalyst, each of which is halogen free, and therefore the halogen content of the resulting unsubstituted or substituted lower hydrocarbon group diphenyl carbonate is not more than 0.1 h ./mln, preferably not more than 10

hours / billion, more preferably not more than 1 hours / billion

The diaryl carbonate obtained in the present invention has a very high purity, and is therefore particularly preferred for use as a raw material for the production of aromatic polycarbonate by transesterification with an aromatic dihydroxy compound.

In addition, aromatic polycarbonate, for the production of which high purity diphenyl carbonate obtained using the present invention was used, was not painted and has high quality and good performance. Therefore, polycarbonate can preferably be used in the form of optical discs that are carriers of information, music, images, etc., or as any of various structural plastics. A method for producing aromatic polycarbonate by transesterification between the high purity diphenyl carbonate of the present invention and an aromatic dihydroxy compound may be any method; but a particularly preferred method that provides good use of the high purity diphenyl carbonate properties of the present invention is the method proposed by the applicants of the present invention, in which the polymerization is carried out while the molten prepolymer digs along a guide fixed in space (see, for example, \ ¥ O 99 / 64492).

The material from which the reaction distillation column is made, a high boiling material separation column A, a diaryl carbonate purification column B, an intermediate boiling material separation column and other liquid contacting parts used in the present invention is typically a metal based material such as carbon steel or stainless steel. In terms of the quality of the diaryl carbonate produced, stainless steel is preferred.

Examples

Further, the present invention is described in more detail with reference to the following examples, but the present invention is not limited to the examples. The purity of diphenyl carbonate and the content of impurities were measured using the gas chromatographic method, and the halogen content was determined by ion chromatography.

Example 1. The reaction distillation column.

The continuously operating multi-stage distillation column shown in FIG. 1, which has L = 3100 cm, Ό = 500 cm, L / O = 6.2, η = 30, Ό / άι = 3.85, and Ό / ά ₂ = 11.1. In this example, two Me11arak sets (total number of steps 11) are installed in the upper part as an internal element, and mesh plates, each of which has a cross-sectional area of one hole of approximately 1.3 cm ² and a number of holes of approximately 250 / m ² , are used in the lower part.

A high boiling material separation column A.

As the separation column A, a continuously operating multi-stage distillation column shown in FIG. 2, which has L _A = 1700 cm and Ό _Α = 340 cm and which contains a nozzle Me11arak with η _Α = 30 installed in it as internal elements.

Diaryl carbonate B purification column

As a purification column B, a continuously operating multi-stage distillation column shown in FIG. 2, which has L _B = 2200 cm and Ό _Β = 280 cm and which contains three sets of Me11arak with u = 12, η ₂ = 18 and η ₃ = 5, installed in it as internal elements.

The column separation of the material with an intermediate boiling point C.

As a material separation column with an intermediate boiling point C, a continuously operating multi-stage distillation column shown in FIG. 2, which has L _c = 1500 cm and Ό _ο = 150 cm and which contains three sets of Me11arak with η ₄ = 6, η ₅ = 10 and Ts5 = 7, installed in it as internal elements.

Reaction distillation.

The starting material used is a reaction mixture containing 18.7 wt.% Methyl phenyl carbonate, which is obtained by introducing phenol and dimethyl carbonate containing anisole into

- 19 011827 transesterification reaction. This starting material contains 27.5 wt.% Dimethyl carbonate, 8.2 wt.% Anisole, 43.9 wt.% Phenol, 1.5 wt.% Diphenyl carbonate, 0.1 wt.% By-products with intermediate boiling points and 110 ppm of high boiling point by-products and additionally contains 100 ppm of Pb (ORy) ₂ as a catalyst. The starting material is essentially halogen free (below the limit of determination by ion chromatography, i.e. 1 ppm or less).

The starting material is introduced into the reaction distillation column (see Fig. 2) at a flow rate of 83.33 t / h from the input of the starting material 101 mounted between the Me11arak nozzle and the mesh trays. The reaction distillation is carried out continuously under conditions when the temperature at the bottom of the column is 210 ° C, the pressure at the top of the column is 3 × 10 ⁴ Pa and the reflux ratio is 0.3.

Separation, purification and reuse by recycling.

The high boiling point reaction mixture containing diphenyl carbonate is continuously withdrawn from the bottom of the reaction distillation column and continuously fed into the lower part of the separation column of the high boiling material A from the inlet A1. Distillation separation is carried out continuously under conditions when the temperature at the bottom in the separation column of high-boiling material A is 205 ° C, the pressure at the top of the column is 1900 Pa, and the reflux ratio is 0.6. The column top product (A _t ), continuously discharged from the top of the high-boiling material separation column A, is continuously fed to the diaryl carbonate B purification column from inlet B1. Distillation separation is carried out continuously under conditions when the temperature at the bottom in the separation column of high-boiling material A is 208 ° C, the pressure at the top of the column is 5000 Pa, and the reflux ratio is 2.0. Diphenyl carbonate is continuously withdrawn from the side stream output of the B2 purification column B.

The top product from the column (W), continuously discharged from the top of the diaryl carbonate B purification column, is continuously fed to the material separation column with an intermediate boiling point C from inlet C1. Distillation separation is carried out continuously under conditions when the temperature at the bottom in the material separation column with an intermediate boiling point C is 170 ° C, the pressure at the top of the column is 4800 Pa, and the reflux ratio is 0.5. A material with an intermediate boiling point, containing by-products with intermediate boiling points as the main product, is continuously withdrawn from the output of the side stream C2 of the material separation column with an intermediate boiling point C. The upper product from the column (C _t ) is continuously discharged from the top of the material separation column with an intermediate boiling point C, recycle and, therefore, reused by continuous feeding into the reaction distillation column. The bottom product from the column (C _B ), continuously discharged from the bottom of the separation column of material with an intermediate boiling point C, is recycled, and therefore reused by continuously feeding high-boiling material A to the separation column.

When all the distillation columns have reached a steady steady state, the flow rate of the feed to the reaction distillation column is 83.33 t / h for fresh material and 3.33 t / h for the top product from the column (St) from the material separation column with intermediate boiling point C, which is recycled and reused, that is, a total of 86.66 t / h The flow rate of the high-boiling reaction mixture continuously discharged from the bottom of the reaction distillation column is 10.00 t / h, and its composition is 0.1 wt.% Dimethyl carbonate, 0.05 wt.% Anisole, 1.2 wt.% Phenol, 29 5 wt.% Methyl phenyl carbonate, 68.0 wt.% Diphenyl carbonate, 0.25 wt.% By-products with intermediate boiling points and 0.9 wt.% High boiling point by-products, including the catalyst.

The flow rate of material supplied to the high-boiling material separation column A is 10.00 t / h for the reaction mixture described above and 1.11 t / h for the bottom product from the column (C _B ) from the material separation column with intermediate boiling points C, which is recycled, and therefore reused, that is, a total of 11.11 t / h. The flow rate for the top product from the column (At) continuously discharged from the top of the separation column of the high boiling material A is 10.56 t / h. The flow rate for the top product from the column (W) continuously discharged from the diaryl carbonate B purification column is 4.50 t / h, the flow rate for the lower product from the column ( _B ) is 0.22 t / h and the flow rate for the side product columns (B ₃ ) is 5.84 t / h. The flow rate of the top product from column (C _T) continuously withdrawn from the separation column with the material of the intermediate boiling point C is 3.33 t / h, the flow rate of the bottom product from column _(S) is 1.11 t / h and the flow rate for the product withdrawn from the side of the column (C ₃ ), is 0.06 t / h

The composition of the product withdrawn from the side of the column (C ₃ ) from the material separation column with an intermediate boiling point C corresponds to 0.7 wt.% Phenol, 24.3 wt.% Methyl phenyl salicylate, a total of 37.6 wt.% By-products with an intermediate boiling point (34.2 wt.% Methyl methoxybenzoate, 3.2 wt.% 2-methoxyethyl phenyl carbonate and 0.2 wt.% Cresylphenyl ether), 38.8 wt.% Diphenyl carbonate and 0.3 wt.% High boiling point by-products, and therefore By-products with intermediate boiling points are concentrated in this product. The top product from the column (St) from the column of separation of material with an intermediate boiling point C contains 8.5 wt.% Phenol and 90.5 wt.% Methyl phenyl carbonate. The lower product from the column (C _B ) from the separation column of material with an intermediate boiling point C contains 1.8 wt.% Methyl phenyl carbonate

- 20 011827 and 97.2 wt.% Diphenyl carbonate.

The diphenyl carbonate content of the product withdrawn from the side of the column (B ₈ ) from the diaryl carbonate B purification column is at least 99.999% by weight; and by-products with an intermediate boiling point and high-boiling by-products are not determined, i.e. their content is not more than 1 ppm. In addition, the halogen content of diphenyl carbonate is also not determined, that is, this content is not more than 1 ppm.

Thus, it is entirely possible to continuously carry out the reaction distillation described above and separation / purification by distillation stably for 5000 hours; all the analytical data after 500, 1000, 3000 and 5000 h have approximately the same values as above, and therefore it is quite possible to stably produce high purity diphenyl carbonate, essentially free of by-products with intermediate boiling points, and high-boiling by-products .

Comparative example 1.

The reaction distillation and separation / purification by distillation is carried out using the same method as in Example 1, except that a material separation column with an intermediate boiling point C is not used, but to some extent the top product from the column ( _Bt ) from the column purification of diaryl carbonate B is reused by recycling to the reaction distillation column. After 50 hours, diphenyl carbonate is obtained with approximately the same results as in Example 1, but then the content of by-products with intermediate boiling points, such as methyl methoxybenzoate and 2-methoxyethyl phenyl carbonate, continuously grows and becomes 10 ppm after 100 hours, 25 ppm after 200 hours and 40 ppm after 300 hours

Example 2

The reaction distillation and separation / purification by distillation is carried out using the same method as in Example 1, except that the conditions for separation / purification by distillation are changed to a temperature at the bottom of the column of 210 ° C, a pressure at the top of the column of 3800 Pa and a reflux ratio of 0, 61 in the case of a separation column of high-boiling material A, up to a temperature at the bottom of the column of 220 ° C, a pressure at the top of the column of 6700 Pa and a reflux ratio of 1.5 in the case of a purification column of diaryl carbonate B, up to a temperature at the bottom of the column of 200 ° C, a pressure at the top of the column of 2400 Pa and reflux chi 0.35 in the case of a material separation column with an intermediate boiling point C. The purity of diphenyl carbonate after 500 hours and 1000 hours is at least 99.999 wt.% and each of the by-products with an intermediate boiling point and high boiling point by-products is not determined, i.e., their the content is not more than 1 ppm In addition, the halogen content of diphenyl carbonate is not determined, that is, this content is not more than 1 ppm.

Example 3. Using the diphenyl carbonate obtained in Example 1, polycarbonate is produced by the method described in Example 1 of International Publication No. 99/64492. The resulting aromatic polycarbonate having an average molecular weight of 10500 is injection molded at 310 ° C. to obtain a test piece (thickness 3.2 mm). The specified blank for testing has a value of b * 3.2 (this value determines the yellowness in accordance with the method of CHEF) and does not have a yellow tint and is not colored, which is excellent from the point of view of transparency. After grinding the specified workpiece for testing with a grinder, the injection molding of crushed pieces is repeated five times at 310 ° C, after which the value b * of the workpiece for testing thus obtained is 3.5, that is, there is no significant color change. In addition, a test is carried out for heat resistance and durability (120 ° C, 500 h) of the billets for testing (b * value = 3.2) obtained by injection molding of the aromatic polycarbonate described above, after which the b * value is 3.5, i.e. significant color changes are not observed.

In the case of a preform for testing from aromatic polycarbonate obtained in a similar way using diphenyl carbonate containing 150 ppm of both by-products with an intermediate boiling point and high-boiling by-products and having a chlorine content of 0.2 ppm, the value of b * is 3.6. As described above, the b * value of the molded billet after five repeated injection moldings at 310 ° C is 4.2, and the b * value after testing for heat resistance and durability (120 ° C, 500 h) corresponds to 4.0. In two cases, the test blanks were slightly yellow.

Industrial applicability

The present invention can be suitably used as a method that makes it possible to produce high purity diaryl carbonate, which can be used as a raw material for high-quality and having good performance polycarbonate, stably for a long period of time, not less than 2000 hours, in industrial a scale of not less than 1 t / h from the alkyl aryl carbonate-containing reaction mixture obtained by the transesterification reaction between the dialkyl carbonate ohm and aromatic monohydroxy compound.

Claims (30)

1. Installation for the production of diaryl carbonate, where the installation includes: (a) a high-boiling material separation column A, which is a continuously operating multi-stage distillation column having a length of B _A (cm), an inner diameter Ed (cm) and internal elements with the number of steps in them n _A , where L _A , Od and n _A satisfy the following formulas (1) - (3): 800 <b _a <3000 (1) 100 <È _A <1000 (2) 20 <n _and <100 (3) (b) a diaryl carbonate purifying column B which is connected to said separation column high boiling point material A and which is continuously operated multistage distillation column having an output side stream, length b | _; (cm), internal diameter Ed (cm) and internal elements with the number of steps in them n _in , where b _in , and n _in satisfy the following formulas (4) - (6): 1000 <b _at <5000 (4) 100 ^ _at <1000 (5) 20 <p _at <70 (6) (c) a separation column C for a material with an intermediate boiling point that is connected to said diaryl carbonate B purification column and which is a continuously operating multi-stage distillation column having an outlet side shoulder strap, length L _C (cm), inner diameter E _C (cm) and internal elements with the number of steps n _C in them, where L _C , O _C and n _C satisfy the following formulas (7) - (9): 800 <b _s <3000 (7) 50 <0 _s <500 (8) 10 <n _s <50 (9) 2. The installation according to claim 1, where the specified reaction distillation column is a continuously operating multi-stage distillation column having a length b (cm), inner diameter E (cm) and internal elements with the number of steps in them n and having a gas outlet with an inner diameter f (cm) at the top of the column or at the top of the column near its top, liquid outlet with an inner diameter of 6 ₂ (cm) at the bottom of the column or at the bottom of the column near the bottom, at least one inlet equipped at the top and / or the middle part of the column below the output aza, and at least one input, equipped in the lower portion of the column above the liquid outlet, wherein L. ϋ. n, 6 and 6 ₂ satisfy the following formulas (10) - (15): 1500 <b <8000 (10) 100 <O <2000 (eleven) 2 <b / o <40 (12) 10 <n <80 (thirteen) 2 <ϋ / 61 <15 (14) 5 <O / 6 _; <30 (fifteen) 3. The plant according to claim 1 or 2, wherein said diaryl carbonate purification column B is a continuously operating multi-stage distillation column having an input b1 in the middle part of the column, output side stream B2 between the specified input b1 and the bottom of the column and having the number of stages p1 in the form higher input of internal elements B1, number of stages n2 of the internal elements between the input terminal B1 and B2, and the side stream a number of stages n3 of internal elements below the side stream withdrawal B2, the total number of stages (n1 + n ₂ + n ₃₎ equal n _in which n _s n ₂ and n ₃ satisfy the following formulas (16) - (18): 5 <n! <20 (16) 12 <n ₂ <40 (17) 3 <n ₃ <15 (18) 4. Installation according to any one of claims 1 to 3, where the specified separation column C for a material with an intermediate boiling point is a continuously operating multi-stage distillation column having an input C1 in the middle of the column, the output of the side stream C2 between the specified input C1 and the bottom of the column and having the number of steps n ₄ in the form of internal elements above the input C1, the number of steps n ₅ in the form of internal elements between the input C1 and the output of the side shoulder strap C2 and the number of steps n6 in the form of internal elements below the specified output of the lateral shoulder strap C2, and the total number of steps (n4 + n5 + n6) is equal to nS, where n4, n5 and n6 satisfy the following formulas (19) - (21): 2 <n4 <15 (19) 5 <n ₅ <30 (20) 3 <n ₆ <20 (21) - 22 011827 5. An industrial process for the production of high purity diaryl carbonate, in which high purity diaryl carbonate is produced by using as a starting material a reaction mixture containing an alkyl aryl carbonate, which is obtained by the transesterification reaction between a dialkyl carbonate and an aromatic monohydroxy compound; continuously feeding the starting material to the reaction distillation column, which is a continuously operating multi-stage distillation column in which a homogeneous catalyst is located; carrying out both the transesterification and distillation reactions in said column; continuously withdrawing a low boiling point reaction mixture containing the resulting dialkyl carbonate from the top of the column in gaseous form; and continuously discharging the high boiling point reaction mixture containing diaryl carbonate from the bottom of the column in liquid form, where the improvements include at least three continuously operating multi-stage distillation columns according to any one of claims 1 to 4. 6. The method according to claim 5, where at least 1 t / h of high purity diaryl carbonate is produced continuously as a product discharged to the side of column B ₃ from said diaryl carbonate B purification column. 7. The method according to claim 5 or 6, wherein said high boiling point reaction mixture containing diaryl carbonate continuously discharged from the bottom of said reaction distillation column in liquid form is continuously introduced into said separation column of high boiling material A and continuously subjected to separation by distillation to the upper product from column A _t containing diaryl carbonate, and a bottom product from column A _B containing catalyst and high boiling material; said top product from column AT is continuously introduced into said diaryl carbonate purifying column B, and continuously subjected to separation by distillation into a top product from column B _t, product withdrawn laterally column B ₃ and the bottom product of column B _B and said top product from column W is continuously introduced into said column of separation of material with an intermediate boiling point C and is continuously subjected to separation by distillation to the upper product from column C _t containing alkyl aryl carbonate, a side-discharge product Since the column ₃ containing the material with an intermediate boiling point, having a boiling point between the boiling temperature of the alkyl aryl carbonate and diaryl carbonate by the boiling and the underflow from column _S comprising diaryl carbonate. 8. The method according to any one of claims 5 to 7, where the top product from the column C _t from the specified column separation of material with an intermediate boiling point C is continuously fed into the specified reaction distillation column. 9. The method according to any one of claims 5 to 8, wherein the bottom product from column C _B from said column of separation C for a material with an intermediate boiling point is continuously fed into said column of separation of high-boiling material A. 10. The method according to any one of claims 5 to 9, wherein said reaction distillation column is a continuously operating multi-stage distillation column having a length b (cm), an inner diameter Ό (cm) and internal elements with the number of steps n in them and having an output gas with an inner diameter f (cm) at the top of the column or in the upper part of the column near its top, liquid outlet with an internal diameter f (cm) in the bottom of the column or in the lower part of the column near its bottom, at least one input located at the top and / or in the middle of the column n below the gas outlet, and at least one inlet located in the lower part of the column above the liquid outlet, where b, Ό, n, f and f satisfy the following formulas (10) - (15): 1500 <b <8000 (10) 100 <Ό <2000 (eleven) 2 <b / n <40 (12) 10 <n <80 (thirteen) 2 <Ό / φ <15 (14) 5 <Ό / φ <30 (fifteen) 11. The method according to any one of claims 5-10, wherein said diaryl carbonate purification column B is a continuously operating multi-stage distillation column having an input B1 in the middle of the column, output side stream B2 between the specified input B1 and the bottom of the column and having the number of steps u in the form of internal elements above the input B1, the number of steps n ₂ in the form of internal elements between the input B1 and the output of the side strap B2 and the number of steps p ₃ in the form of internal elements below the output of the side strap B2, the total number of steps (u + p ₂ + p ₃ ) equal to n _B , where n, n2 and n3 satisfy the following formulas (16) - (18): 5 <u <20 (16) 12 <n ₂ <40 (17) 3 <n3 <15 (18) 12. The method according to any one of claims 5-11, wherein said column for separating material with an intermediate boiling point C is a continuously operating multi-stage distillation column having an input C1 in the middle of the column, outputting a side stream C2 between said input C1 and the bottom of the column, and having the number of steps n ₄ in the form of internal elements above the input C1, - 23 011827 the number of steps η ₅ in the form of internal elements between the input C1 and the output of the side shoulder strap C2 and the number of steps η ₆ in the form of internal elements below the indicated output of the side shoulder strap C2, and the total number of steps (η ₄ + η ₅ + η ₆ ) is n _s, where η _4, η η ₅ and ₆ satisfy the following formulas (19) - (21): 2 <η4 <15 (19) 5 <η5 <30 (20) 3 <η6 <20 (21) 13. The method according to any one of claims 5-12, wherein each of said reaction distillation column, said high boiling material separation column A, said diaryl carbonate purification column B and said column C for separating intermediate boiling material is a distillation column having a plate and / or nozzle as internal elements. 14. The method according to item 13, where the specified reaction distillation column is a distillation column having as an internal element a nozzle in the upper part of the column and a plate in the lower part of the column, and the internal elements of each of the specified column separation of high-boiling material And the specified column cleaning diaryl carbonate In and the specified column separation of material with an intermediate boiling point C is a nozzle. 15. The method according to item 13 or 14, where the specified nozzle is a structured nozzle of at least one type selected from the group comprising Me11arak, Scrack. CLOSE-CANCER, Р1ех1рас, nozzle ^ ikeg, nozzle ΟοοάΓοΙΙ and ΟΙίΙοΗβΓίά. 16. The method according to item 13 or 14, where the specified plate in the specified reaction distillation column is a mesh plate having a mesh part and an overflow part. 17. The method according to clause 16, where the specified mesh plate has from 100 to 1000 holes / m ² in the mesh part. 18. The method according to clause 16 or 17, where the cross-sectional area of one hole of the specified mesh plates is in the range from 0.5 to 5 cm ² . 19. The method according to any one of paragraphs.5-18, where the distillation operation in the specified column separation of high-boiling material A is carried out at a temperature below the column T _And in the range from 185 to 280 ° C and at a pressure above the column P _And in the range from 1000 to 20,000 Pa 20. The method according to any one of claims 5-19, wherein the distillation operation in said diaryl carbonate B purification column is carried out at a temperature at the bottom of column T _in the range of 185 to 280 ° C. and at a pressure at the top of column P _in the range of from 1000 to 20,000 Pa . 21. The method according to any one of claims 5-16, wherein the distillation operation in said column C for separating material with an intermediate boiling point is carried out at a temperature below the column T _C in the range from 150 to 280 ° C and at a pressure above the column P _C in the range from 500 to 18000 Pa. 22. The method according to any one of claims 5-17, wherein the reflux ratio for said high boiling material separation column A is in the range from 0.01 to 10. 23. The method according to any one of claims 5-18, wherein the reflux ratio for said diaryl carbonate B purification column is in the range from 0.01 to 10. 24. The method according to any one of paragraphs.5-19, where the reflux ratio for the specified separation column With material with an intermediate boiling point is in the range from 0.01 to 10. 25. High purity diphenyl carbonate produced by the method according to any of claims 5-24, wherein diphenyl carbonate is an unsubstituted or substituted lower hydrocarbon group and has a halogen content of not more than 0.1 ppm, the content of said material with an intermediate boiling point of not more than than 100 ppm and the content of by-products having a higher boiling point than diphenyl carbonate, not more than 100 ppm. 26. The high purity diphenyl carbonate according to claim 25, wherein the diphenyl carbonate is an unsubstituted diphenyl carbonate and the halogen content is not more than 10 ppm, the content of said material with an intermediate boiling point is not more than 30 ppm and the content of each of phenyl salicylate , xanthon, phenylmethoxybenzoate and 1-phenoxycarbonyl-2-phenoxycarboxyphenylene, which are by-products having a higher boiling point than the boiling point of diphenyl carbonate, is not more than 30 ./mln. 27. The high purity diphenyl carbonate according to claim 25, wherein the content of said material with an intermediate boiling point is not more than 10 ppm and the content of by-products having a boiling point higher than the boiling point of diphenyl carbonate is not more than 50 ppm. million 28. The high purity diphenyl carbonate according to claim 27, wherein the halogen content is not more than 1 ppm and the content of by-products having a higher boiling point than the boiling point of diphenyl carbonate is not more than 10 ppm. 29. A method for the production of aromatic polycarbonate, which includes the use of high purity diphenyl carbonate according to any one of claims 25 to 28 as a raw material for the production of aromatic polycarbonate by transesterification with an aromatic dihydroxy compound. 30. Aromatic polycarbonate obtained by the method according to clause 29.